This is a weird one. So i recently bought an 2002 wrx 50,000 miles. The guy i bought it from didn't know anything about the car or what has been done to it. The car had a bigger turbo in it, but was replaced because it was starting to go. It was replaced with a stock turbo, or one of the same size. Now for the problem. When i go wide open, right around 4k rpms the car starts bucking/jerking pretty bad and i loose all my power. Its been so bad at times it moves your body hard in the car. If i push in the clutch and rev it out, it's fine, so it only happens when under stress. I had a feeling my ECU must not be working properly, so i knocked on my MAS and moved some wires and it work fine. In about a day it started doing it again. Could a MAS allow this to happen? I've gotten tips that maybe the turbo could pushing so much pressure at the high rpms that its closing off a vacuum line? I'm open to all suggestions before i go drop the money on a new sensor.