Idk my dad bought it new is 94 and put over 500,000 on it and jus sold it.

 

Do you have black smoke coming out of the tailpipe? If you have a scan tool, hook it up and take a look at everything just to be sure. I assume your check engine light is on, or at least was at one point. If so, get it hooked up to a scan tool and look at the freeze frame data from when the code was thrown...that will probably be the best way to diagnose this being that its an intermittent problem.

 

The only time I have noticed any smoke at all is when it happens to restart shortly after going dead. (very rare that it will restart) No smoke while driving or when starting after it has sat for a while. It certainly doesn't act like it is running rich either...it never sputters...it's just running, or not running, and will not try to fire at all when it has quit and trying to restart.
I don't have all the tools I need to diagnose this problem. I have found a mechanic who I trust enough to not start just replacing parts in hopes of finding the problem. Truck goes in next week (Tue.) I'll post here what he finds.
Sure am getting tired of people giving me the old "number one" wave as I sit dead in the left turn lane during rush hour!!

 

I had a similar thing happen to me with a used car I once bought. It would run fine, then suddenly buck and stop, especially when I put a load on it like climbing a hill or acceleration. Turned out to be the most clogged air filter I ever saw. It could also be an failing ignition part. In the olde days it could have been a bad rotor, condenser or cracked distributer head. Whatever it is, I'll bet it's not too serious.
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2012 FX4 EB Max Tow white, build date next Tuesday

 

x2 on failing ignition part. If you don't get spark, youll flood the cylinders and once it does decide to fire, itll burn all the fuel with a lot left over i.e. black smoke.

 

I had an 86 Ranger that would do the same thing, only it would start right back up. Turned out to be the computer. This Ranger would always get 24mpg on the road running 75 to 80, after the computer switch it never got over 20. It didn't die anymore though.