When did it start doing this? Before you installed all those parts? If it started after you installed those parts, check your new parts against your old parts. (cap & rotor!!) Make sure you put the cap on right with the plug wires in the correct firing order.
If it happened all of a sudden while you were driving or starting to drive it, there could be a timing chain problem. Although, you have not mentioned what engine it has so it's hard to say what else it might be.
If it has a catylitic converter, that could be plugged. Check fuel pressure by disconnecting the fuel hose to carb and inserting that business end into a bottle and crank the engine for a few seconds. As mentioned before, deisel bad - gas good (LOL)
Check your oil. A guy last week said almost the same thing and found out his oil filter had a big hole in it and all the oil in the engine was gone. Too much friction - bad....
Will it rev up in neutral? does it backfire? does it have good spark? You sure you got the plug wires right? that's about all I can think to check.
85 CJ7 4.0L/SM465/Dana300/AMC20/Dana30, MPFI,154K miles - 33" 12.5's Pro Comp MT's, one piece axles, Detroit Softlocker rear, Lock Rite front, Warn Hubs, 4.56 R&P, 4" BDS lift, Warn x8000i, Warn winch guard, Hi-Lift, Tuffy console, Four X Dr. rocker guards, Rock Hard sport cage, Kilby OBA with 1.75 gal tank and York 10.3cc compressor, Tube fenders by GenRight Offroad, Fabricated rear bumper and tire carrier.