Decided to learn playing leads on the guitar after almost 40 years.

I was kinda forced into it at first. My band used to have 3 guitar players with me playing rhythm and doing lead vocals. When our primary lead player left it was obvious that our secondary lead player was not up to the task and I was getting frustrated as hell. That's why I decided to pick up the ball and run with it.
What I did was add three songs to the set list. They were Jessica (Allman Bros.), Black Magic Woman/Gypsy Queen, and REO Speedwagon Roll with the changes.
I figured that Jessica would teach me about fairly clean single note leads, The Santana song would help with smooth sustained tonal bends and working in "the groove" of the song, and finally, Roll with the changes would give me a taste of fast distorted leads. It has been a blast and the band has a new life.
After 5 months I am there and they are on the set list. The best part is that they are right on the money and I am loving it. The toughest one is the REO because I do all the guitar work plus the lead vocal but it works.
I guess my point is that you are not too old to try new things and it can be well worth the effort.

I've gotten better with inflection, pick attack, bends, etc., but my speed and accuracy on anything at a decent speed are just horrible.

Your articulation and accuracy will increase if you focus on just a couple positions on the neck, no matter the key.

A good "excercise" is to just find that comfortable position and run three notes on one string then down to the next. All six going up. Then all the way down again. You'll get 11 notes that way.

Then, move down one string and repeat the action. Do that with three sets of two, like strings 5 & 4, 4 & 3, and 3 & 2. You'll introduce some flatted 2nd or 6ths. The playing will sound modal, and might be more interesting to your ear, and it will increase your speed since you're staying in a comfort zone.

Eventually, you will get confortable in multiple areas of the neck and you can start moving from spot to spot.

Worked for me.
GAC

"run three notes on one string then down to the next. All six going up. Then all the way down again. You'll get 11 notes that way." I'm not sure what you meant there. I'm pretty familiar with the frets/notes on each string, so if it's easier to express it that way... thanks.

I reread my post and unless i was actually showing you, it would be very confusing.

Let's say you want to play in E.

So go to the E on the 5th string, 7t fret. Play 7, 8, 10, then drop to the 4th string and play the same frets, then work back, without repeating the 10th fret on the 4th string.

So, you'd play 5:7, 5:8, 5:10, 4:7, 4:8, 4:10, 4:8, 4:7, 5:10, 5;8, 5:7.

Now you drop to 4:7 and repeat that pattern into the 3rd string and so on. Doing this on pairs 5/4, 4/3, 3/2, and 2/1 gives you an ascending run, with internal descensions, that covers 44 notes. It also introduces some interesting flatted elements like the flatted 2nd and flatted 6th.

Now, if you make the 2 fret jump as your second note, (skipping from 5:7 to 5:9) you now have a standard second and sixth. What i find useful is to do both of those so you mix and match these two moves after a while and you'll find that there are 4 different modes being played without even moving the hand.

Now, if you get comfortable with that run, you apply the same approach but now starting at 3:9, which is also an E. This allows you to extend the range of the run to two full octaves without moving your hand more than 2 inches.

You can get interesting and non-reptitive solos that aren't locked into the standard blues box and not have to move your hand move than an inch and a half.

The other thing you might want to learn to do (lots of the great do this) is play through the changes. Don't feed like every phrase has to end at the chord change and start over. Think sax. Hardly any truly great sax players worried about starting a new phrase on the change. And sax players are among the best linear and modal players we're likely to hear. (I guess trumpeters too.) That's pretty easy. Listen to the song and your own playing. If you already play a phrase past the chord change, you already do it. If not, you just have to work on NOT doing something like cutting off your line just because the E is about to change to an A.

THe reason i bring these both up, is that i've seen a lot of new learners feel they have to move to the chord or totally think in the key of the chord when it's changed.

The idea i first proposed will allow you to play nice lines with interesting substituted notes here and there that, because of the 11 note sequence almost forces you to think of the line and not of the chord coming up. Don't know if you will like this or not, but it really works for me and a couple of the students i had that really worked at it and stayed with guitar over the years tell me it works for them too.
GAC

start slowly with the run then pick up speed. The thing is you do it over and over again. Repetition seemed to be the key to get my fingers moving. I always thought that I just had slow fingers and that was that. Not the case at all. It is like anything else, you have to practice. The songs I picked were tunes that I basically had the complete lead already in my head because I liked them so much.
Cheat. Use guitar tabs to get you in the right place to begin with and take it from there.
If you know someone that already plays guitar ask them to listen to you and for help. I was doing the REO tune and our other guitar player said that there were a lot of double bends in there. I asked him what they were and he showed me. Easy enough and I learned something new. In Roll with the Changes there is a fast run of double bends up, down, and up the neck again after the first verse. It was cool but more important, when I did it my confidence shot right up.
I also found that there were times I would want my hand loose and fluid and other times I needed it anchored firmly in order to accurately pick repetitive fast notes.
One other thing, the more relaxed I was the better the playing. So chill out.
I was easily intimidated by lead players. Our band used to do Jessica with the old lead player we had. I used to think it was great but it turned out that I wasn't really listening. When I started doing the lead with the band I couldn't figure out why the guys would lose me at a particular spot every time. Turns out they said that Joe never played that part. When I listened to a live recording of him playing the tune it turned out he wasn't anywhere close to the original lead. He just did runs in D. I learned it by doing exactly what Dickie Betts was doing in the studio version though live I don't think he plays it the same way twice. For now I stick with doing it the way the original was done because I need the foundation and as I get more comfortable I will branch out.
I have found that if you want to be a better guitar player then play with those that are better than you. LOL, it seemed for a while that everyone could run circles around me when it came to leads. Rhythm is an entirely different story. That was my spot.

I just get frustrated at times, but I know I need to keep going.

. . .of The Cars, but Elliot Easton is a great guy to learn from. All the tricks are in there somewhere but his playing is so musical that they become songs within the song.

You can learn an awful lot from him and his solos definitely run through various degrees of difficulty.

I learned almost ever Cars' solo ever. (Well, maybe not from the last album.) But, definitely from the first half-dozen. He's just such a tasty player.
GAC

You're right. He is an awesome, musical player. Not the flashiest or fastest, but his solos are really memorable. Great rhythm player, IMO. Again, not the flashiest, but great nonetheless. Not extremely difficult to learn either.

Thanks for the suggestion.

Whenever I am working on a lead I did not write, I always start slow.

1. Learn the notes, the fingering and transitions.
2. Once you know where your fingers have to go on the fretboard start slow using the metronome.
3. Repeat, repeat, repeat the leads.
4. Slowly bring the speed up to the level you will be playing at and repeat, repeat, repeat...
5. Go beyond that speed if possible. That way you will boost your confidence in executing it.
6. Good luck!