'95 OLDS 88 engine problems!

I hope someone can help me! I have a '95 Old 88 with the 3800 series engine. When you first start the car and try the rev it up it wants to hesitate. but in 30 seconds it revs up fine. Also if you let the car sit 30-45 minutes after driving it and go to start it, it will start but it acts like it is flooded and shakes real bad for about 10 seconds. The check engine light comes on and off every few days. I've had the codes read but that turns up nothing! I've change plugs, it just had a new $600 computer put in, new air and fuel filters, a new PCV valve. Does anyone have any idea what this is? Or give me some info to go on? Any help would be greatly appreciated! Thanks. Kevin

Could be a bad fuel pressure regulator. See if there is gasoline in the vacuum line going to the regulator. If so replace it - let us know.

$600 on an ECM??? You. Got. Ripped. Off.

Check the fuel pressure, it should be around 40PSI. After that, you ought to clean the TB, MAF, and IAC. http://www.lesabret.com/phpBB/viewtopic.php?t=4054

One quick question,have you been loosing coolant lately?

No, I'm not losing any coolant. And there is not gas in the fuel pressure regulator vacuum line. Kevin

Have you found the problem?

No, I haven't found the problem. I cleaned the MAF and IAC sensors and the intake where the butterflies are, like the link showed in detail, but still the car has no get up and go! What else should I look for or try. Thanks Kevin

Since I'm no specialist I can only grasp at straws. If it were supercharged I'd say the supercharger belt is slipping. This happened to me. I'm not sure if a clogged cat could cause this but it may be worth checking. Also, start it up at night when it's real dark and see if there is arcing from the plug wires. If not spray water on them and see if they arc.
That's all I have for you.

Thanks guys for the great info so far! How is an easy way is check a cat. converter? Thanks again! Kevin