I am new to this forum but have been reading a lot of them. I am working on my neighbors jeep (1995) and the problem is, it will start up and idle fine. As soon as you hit the throttle to rev the engine the Rams go up normal, good throttle response and then the Rams drop below the 750-900 rpm mark and idles rough for about a minute and then comes back up and idles fine. When I test drove it, it takes off ok at first but if you hold steady on the throttle it bucks a bit. If you lift off from the throttle such as coming to a stop, it drops the Rams real low and almost stalls.
So far the things that have been replaced on this vehicle: PCM , ICM , TCM , O2 sensor, cap, rotor , wires , plugs, coil, as of today the fuel pump because the regulator is built into it , and the fuel filter.
Any and all help would be greatly appreciated.

It has the 5.2 engine, not that it would matter.

 

Well, you threw just about every part I can think of at it. Has anything changed since shotgunning all of those parts at it? I think you're dealing with a leaking plenum gasket on the bottom of the intake manifold. They tend to blow out and will cause a vacuum leak. It will also cause oil consumption. You have to remove the intake in order to replace the gasket.

 

The only thing left that doesn't make any sense to me would be the MAP. Looks like I might be tearing apart the top end. Thanks for your input Bustedback!

 

Well, I spent most of the last day changing out the plenum gasket and intake. Had to replace the water pump as the bearings in that was shot. Got everything hooked back up and fired her up. Purrrred like a kitten and even had better throttle response. She would come down off rev and hold the RPMs great,............for about a minute. Now back to the same thing, comes off slight rev with bucking and studder! Same exact thing this has been doing the whole time.��

 

Question for anybody please. What does it mean if you remove the vacuum line from the EGR valve to the sylinoid and there is no change in the idle? I did this and for right now if I rev it and let off, it does not bog out anymore. Sounds like I am finally on to something but not sure if it is the valve, the sylinoid or maybe even the cat. Any help please?