This has plagued me for months and when I lay in bed it haunts my dreams. I'm testing everything, 8 times over. What have I done to the car, which upgrades all at once that would cause this. Bigger intake/IC piping, sucking more air in? No cause the MAF will take care of that. Bigger exhaust, maybe a leak in the pipes because it's hard to fit 3" of turbo exhaust in the car. Ok buy a smoke machine and check for exhaust leaks... No leaks. Go back and check intake again, it slowly holds pressure at an acceptable rate. grrr. Maybe it's a bad sensor, bad ground, bad wiring...
Putting on a smaller brake booster to fit in the 3" exhaust piping, my brakes were mushy and you had to put a little bit of force on them. I thought, I haven't driven a grandprix in a year since tha accident, i'm using my left foot now, this new car has 13" brakes upfront, 12" on the rear, smaller brake booster, SS lines instead of plastic, it just must be a little more soft then normal. A few times it's crossed my mind to plug the brake booster line to cancel that equation out of the system, because I've plugged every other vacuum source. Then I'd fall alseep and forget.
My trims are starting to move back to zero. Dam the brake booster.
