just replaced the alternator not too long ago,

battery seems to be charging,

sometimes it takes 3 tries to start the truck, kind of like stress on the starter motor, (starter was changed a couple of years ago)

it cut off on me, and wouldnt start, left it sitting for a while, and it cranked right up,

any ideas?

 

I had a similar issue on a pontiac I owned, would start fine when cold but once was warmed up to operating temp the starter could barely turn the engine over. Turned out the started was bad, replaced it and has started effortlessly ever since.

 

your description of the symptoms is not really clear.
is your starter turning slowly, and sometimes not at all ?
a 2 year old starter may, or may not be good.
i would start with a good visual inspection of the battery cables.
if those pass the visual inspection the next thing i would do is test for voltage drop at the starter. if you aren't familiar with that, check youtube; there are plenty of good videos on this and it's quite simple.

 

You can check the timing as well. I bumped my timing up to 12 degrees to see if it would affect my gas milage and drove it a couple tanks of gas. It was about 4 degrees the other day and I drove about 8 miles to get a chair, I turned off my pickup, went in the store, came right out and it turned over once and nothing. I tried it again and it was like a dead battery hardly turning over but it started. My optima red top is is around 8 years old, my starter has probably 20k miles on it, autolite starter. I read something about timing and remembered I had bumped mine up. I put a new mark with white paint on the 10 degree line, got the pickup warm again, turned it off and it started ok a couple times. I turned it back off, loosened the hold down on the dist, pulled the little plug you pull when you time it, connected my timing light. I went to start it and it barely started like when I was at the store! I adjusted the timing to 10 degrees, locked the dist down, turned off the pickup and disconnected everything, put the little plug back in that I pulled to time it. I started and turned it off a few times without any issue. I have driven it a week now with no issues.

If that doesn't fix your issue, I would change the starter and try to find an autolite starter somewhere, I have always had the best luck with those.

 

What is the engine and transmission