GTI 337/20th Anniversary :: Won't Accelerate Smoothly?

A couple months ago i posted that i had some choppy acceleration. I didn't do anything about it because I was looking for my vag-com cable but couldn't find it. well, i still haven't found it but my problem is getting worse. I have an older version of vag-com 303 and i think that it only supports serial.

Let me also describe my problem and what i have done so far to try and remedy it: basically, when i start to accel from a stop it doesn't accel smooth and feels like it is about to go limp and then all of a sudden i get this burst of accel. it is much more noticeable when accel from a stop but it is also noticeable when pressing the throttle, just does not accel smooth and once in a while, i get this sudden burst of power. And the car has gone into some kind of limp mode twice so far.

Once with my wife and just the other day when i was on the freeway, i lost all power and the EPC light came on and the ESP round arrow thingy. i pulled over, shut off the car and 30 sec later i was able to start driving again and all the lights went out, but of course, choppy accel still persists. the other day when i was accel i heard a POW from underneath. and my wife tells me she has heard it once before. when i remove the cable from the MAF everything goes back to normal. i cleaned the existing MAF, and when that did not work i replaced the MAF and still the same problem.