car bogging down, not getting all power

[vanhab]

so i bought a 2001 gti with all the upgrades already installed. just as i drove it home like a 30mile drive the engine light came on, so we brought it to the dealer and they didnt know what was wrong. so i was driving it and all of a sudden it started jolting and than it wouldnt alcellert good, if i was supposed to be in 2nd gear i would have to put it in 5 gear to move with out it jolting, and than when it jolts it dies at every stop sign. so we put about $3000 trying to fix it but it never was fixed the place we brought it to has no idea what wrong, they put a new chip in it and programed it. if anyone has any idea whats going on please help out

[veedubmechanic]

cant really help you w.o knowing the aftermarket parts.. 1.8t or vr6

[edspecR]

"with all the upgrades?"

... whats that mean. mine didn't come with any "upgrades"

[SPORTYGTI]

It Is More Than Likely Your Mass Air Intake Sensor Because My 2001 Vw Did The Same Thing In The Garage And It Wouldn't Go Over 1800 Rpms. A Few Hundred Bucks Will Fix That. This Problem Usually Happens When The Car Isn't Driven In A While.