Well, an update, and a cry for help.

I replaced the injector today that was supposedly causing the problem. It made no difference (like we predicted). The car still runs rough. I did notice that it is not running smooth even at higher rpms. I guess it just has enough momentum at higher rpms to smooth it out a bit. It is really bad at about 1500. It shakes the whole car. When I start the car cold, it runs, slightly rough. After it warms up it runs much rougher. If I run the rpms up to 3-4000, and then let off the gas, it will drop back down to idle rapidly, and die, or sputter really bad and recover.

What I find most strange is it was working perfect, and then turned this way instantly. I would have thought it was a loose hose or a plug for a sensor somewhere.

Here is what I have done:

I did have a leaky spark plug gasket. I fixed that a few months ago. Could oil in the sparkplug well caused any of this? It's all cleaned out now, and the car ran fine for a month or so after I did this repair. I am pretty sure they are unrelated.

I did have a cylinder drop test done. 1,2,3 had very little drop. On 4 the Idle increased temporarily then dropped back down to the same rough Idle. I did find the O2 voltage high, fuel trims up to 50 at times. I guess its just running rich. That is what made the mechanic think the injector in #4 was bad.

I checked the timing. It is correct. I have had the map sensor, 02 sensors, and IAC circuit tests done with a lab scope. All where performing within perameters. I did try a new map sensor like I stated above. There was no difference in Idle. I also had the mechanic force the 02 sensors rich and lean, both reacted properly and seemed to track together @ higher RPM.

My fuel pump pressure is fine, and there was no significant presure drop when I tested the other injectors for leakage.

I am out of ideas. I do not want to take this car to satan or another shop, because I really dont know what else they could check.

Any Help? Thanks in advance!! If I didn't explain anything well enough, just ask and I will clarify. Thanks for all you guys do here!