My jeep acts like it runs on 2 or 3 cyl Help plz

I consider my self a decent mechanic but i am having problems with getting my jeep to run right. It is a 1989 jeep limited wagoneer 4.0 ltr, I have replaced the CPS, ECU, cap, rotor, plugs, wires, fuel pump and fuel filter. Also I did a compression test (avg 148- 152 per cylinder) fuel pressure is at like 35 lbs give or take, and pulled fuel rail out and watched the injectors all squirt nice pattern as I turned it over and the same with spark plugs. It acts like it is slow on timing or n o fuel pressure, it runs at about 300 rpm doesnt take on throttle either, sometimes feather it to idle it up or starting fluid. any suggestions will be appreciated thank you.

I have see a bad plugged catalytic converter choke half the engine out with random misfires,
see http://www.automotiveforums.com/vbulletin/showthread.php?t=972629

Feel the exhaust pressure if it doesn't seem correct disconnect the converter at the front flange. Move back about 1/2 inch if this corrects the problem buy a new converter. I have drilled broken studs out and used a nut and bolt instead.
You can also check for a large intake leak by spraying carburetor cleaner along the edge of the intake manifold.

Thnx for the ideas, the exhaust is also cut at the turn back by the oil pan. My cousin drove the jeep till the trans starting slipping and changed it. After the new one was installed it is hard to start and barely runs but will idle round 300 rpm and just noticed there is no o2 sensor hooked up. Wander if that could do it or the map sensor, but i will check the intake gasket in the morning. Thnx again for the replies :smokin:

Definitely hook up the oxygen sensor and the map sensor. All of these items are needed.

Yes check the oxygen sensors, the computers will think all kinds of crazy things if the o2 sensors are covered with carbon or malfunctioning etc. And I agree with the map Sensor and a plugged cat or exhaust system somewhere.