This has been going on for about 3 Weeks, the car has not been driven at all since the problem has started and has been in my shop. We just replaced the Opti, water pump, coil, plugs, wires, Map sensor. WE we are still having the same problems with the car. We hooked the scanner back up and we got the code P1661, (MIL control circuit problem), and Code P0300 (Random Cylinder Misfire)
In the misfire data 2 4 6 and 8 are currently missing. 02 sensors are crossing Great, both 02 B1S1 and B2S1 are Very similiar. We are using a Snap on scanner also, its not missing on all Four at the same time, acts like a CTS problem, Cold start it does ok, once it starts warming up the problems gets worse, Backfire out the Exhaust and it does have a miss that comes and goes on different cylinders. CTS is reading accuratly so is the IAT. We do have the SLP air temp mod, which is different from the CTS but nothing out of the ordinary.

We have 3 machanics looking at the car and we are all very knowledgable. This is stuping us very much, we are kinda of embarrased about it. We are leaning toward a Quad malfunction in the PCM.
PLEASE I NEED HELP

 

sounds like the plug wires on the 2-4-6-8 side are mixed up, I'd double/triple check those, did you also replace your ICM with everything else? weird issue.. might very well be the pcm ?

 

Well the wires are correct (I am sure of it) I do have OVC setup but I checked them many times. The car is running very rich. we even have new Ac delco 02's. This is very depressing, I am sending my computer off to Bryan tomarrow and see if it is indeed the PCM.