[Shogun]

Sounds to me that your reg is fine simply because the pressure changes. A slow rev will still allow all vaccum devices to operate because the cylinder is not in demand of all of the air entering the system. Where as a snap rev of the throttle will cause the throttle position sensor to go to max or near max volts telling the computer to supply more fuel which in turn requires more air and all off this happens so quickly the air coming into the engine has only time to get in the cylinder and not sight-see on the way in. Nature is lazy and will always take the least path of resistance. Thus the other vacuum operated systems have no air to work with. Dose it backfire at all (intake or exhaust)? Any black smoke after a shift under hard accleration? How dose it idle? You might have a vacuum leak or even a exhuast leak. Either/or will seriously affect performance. A vaccum leak will cause eradic idle due to unmotiored air to entering the system confusing the computer (so to speak), Also a exhaust leak (even a small one) will cause lowered performance due to lower exhuast temps across the given o2 sensor. Because there are two (o2's) the side with the leak will have a lower temp across that o2 and the side without the leak will be higher in temp, my guess is the computer will see this and add more fuel thinking the actual "good gasket" side is running lean. Because the Adaptive Logic computer will always try to make the engine run as well as it can with the given inputs. And will always opt for the conservitive tune (to prolong engine life). And this is assuming all your sensors are working properly. I am so sorry about the HUGE post but sometimes I just ramble.....You can not affectivly troubleshoot something without first knowing how the system works. my .02 feel free to tell me that I am full of S*%# I may have just made it worse..sorry but when I get started.....