Bought the truck at a title pawn didnt test drive just started it in the parking lot and let sit and idle for about thirty minutes it idled great and sounded good paied for it drove it off the lot it ran perfect got 2 miles down the road and wires caught on fire by the intake and had it towed home got it home it wouldnt crank so i replaced the iwres that were damaged during the small quick fire the truck started but isnt idlesing right it sounds like it has a "Cam" in it and it lacks poewer but it will sit there and run and i've drove it a pretty good ways but anyways the question is is it more likely vaccum problem or maybe a burnt valve the vaccum isnt correct on it! And its a 4 speed and the way its running you cant really use fourth unless its down hill or a straight away  

You might start with a compression check on engine.  

Seems like a similar problem w/the pup I had...back in '95 I had an 82 F250 w/300 inline and the 4spd. Ran great for awhile then it was like it had no power going down the road. couldnt even use 4th. it would spit and sputter when you were on the gas but would idle descent...tuned it up w/the goodies and still wouldnt get out of its way. the last thing I changed (it seems its always the last thing you do) was the ignition box on the LH fender/firewall area. that was the problem, and if I remember right it was a 50 or 60$ part.