Carbureted or Throttle Body Injected? What is the idle normally at? Remove the distributor cap and use a piece of metal to test the magnetic pick up. Rest the metal object on the center piece (the magnet) and see if there is any resistance when you pull away from it. If it is very weak or there feels like there is none at all, replace the distributor (or rebuild it with a new pole piece). This was a common problem in the early 2K's with early to mid 90's trucks. Also look for green or white "fuzz" type corrosion in the distributor.