md_medic

This is my first adventure into forced induction engines. I have had 2 MKIV VR6'SW, 1 MKII 1.8L 16V, 78 DIESEL RABBIT, A 72 914, and numerous other air cooled vehicles. First my current car: 1.8T, Quattro, Tiptronic, Front Mounted Intercooler, Upgraded turbo inlet pipe, 3" turbo back exhaust (with test pipe), modified stock intake (smoothed inside, hole cut in the area near the wheel well double covered with screen) and a K&N filter, and a Speed Tuning Stage II chip. I had been noticing that the car was just not running right at speed, It is hard to explain and could be my imagination but it seemed to almost have a very little buck / surge. To the point lately I have noticed that when the car is under load, such as going up a hill, in tiptronic 5 it would really surge and buck. The vacuum guage said ten and then it would drop down to zero then back to ten. It would do this for as long as the hill was. Well today I was going up an incline in automatic and I really stepped on it and it started to buck and act up, although this time letting my foot off the gas and then pressing it did not good I also noticed that vacuum was at -10-11 when normally it is around -20 (with foot off the gas of course). I pulled over at the top of the hill and was checking things out and In checking to make sure the Mass Air Flow sensor was still plugged in it started to idle fine. Well It was about a mile to my gas station so I drove it with the MAF unplugged. The car ran better than it had been however my boost gauge would not show any boost. These are the following VAG readings I have gotten
This first one is from the gas station right after this happened:
3 Faults Found:
17963 - Charge Pressure
P1555 - 35-10 - Maximum Limit Exceeded - Intermittent
16486 - Mass Air Flow Sensor (G70)
P0102 - 35-00 - Signal too Low
17953 - Throttle Valve Controller
P1545 - 35-10 - Malfunction - Intermittent
Readiness: 0000 0100
I also got this one but my MAF was unplugged at the time
1 Fault Found:
16486 - Mass Air Flow Sensor (G70)
P0102 - 35-00 - Signal too Low
AND THESE ARE TWO COMMON ONES THAT I GET PROBABLY DUE TO TEST PIPE
2 Faults Found:
16806 - Main Catalyst; Bank 1
P0422 - 35-00 - Efficiency Below Threshold
17544 - Fuel Trim: Bank 1 (Add)
P1136 - 35-00 - System too Lean
I would like to know if the MAF has anything to do with the turbo pressure and if this sounds like a MAF problem at all as there was no indication on VAG VOM and the air intake volume was well into the 180's. Any help would be greatly appreciated!