I don't want to argue with the previous post,but I purchased a 95 PSD that was a theft recovery.The engine was sitting in the bed when I purhased the truck,so we put it back in & it ran fine.The only problem was that asw long as you were accelling everything was fine as soon as you reached your target speed & I would only touch the throttle enough to maintane that speed it sounded as though I was driving over rumble strips.I scanned the PCM,did a buzz & cylinder contribution test.This indicated I had a problem cyl.4&6,removed both valve covers to find brand knew AD's in these cylinders.I replaced them with used AA's cured the problem.This leads me to believe that a modded PCM or chip would be needed.
I also believe the of this truck had someone working his truck who didn't have a clue.The owner then became frustrated & did a phony theft to get out from under it.This very nice white crew came from TEXAS.Hope it didn't belong to a member.