I have a 94 jimmy 4.3. it is running rough and occassionally backfire/popping from what sounds lie under the hood. Ivecahnged plugs, wires, egr, oil and filters. tommorrow im changing cap and rotor. Any more ideas??

Have your catalytic converters check, a plugged cat will cause the same symptoms.
It's a cheap test, that canbe done @ any local muffler shop.

I thiink ill just take the cat off since i live in a no e check county. Ill just weld a straight pipe on.

Try doing a fuel pressure test and post back with the results

I changed rotor, cap, feul press. reg. and plenum gasket and truck is running great.

what was it doing? I know it says runing rough, was the inside of your plenium filled with gas? What was the symptoms you had?