97 jeep tj hard to start misses and back fires

I have a 97 jeep tj with a 4.0. I have replaced
distributor, coil, cap, rotor, plugs and wires. New
idle air sensor, new crank sensor, and a new pcm. I
replaced the distributor and then the jeep was very
hard to start and once running it wouldnt rev up,
and spit sputtered and backfires. I put old
distributor back in and no change. Timing is set to
TDC. I have had it in the shop and he said he
thought pcm was bad so I replaced it and still not
any better. Idles fine once running but cant rev up
At all. Any ideas?