Contaminated MAFs
Yes, I agree that the MAF contamination is a very common problem.
I am sure they contaminate over time when using ANY of the oiled cotton gauze filters. They will gradually degrade the accuracy of the MAF to input accurate readings to the processor to control A/F mixture. I also found the CRC QD cleaner to work the best without touching the sensors. I also clean mine when cleaning the filter. Over oiling the filter is also easy to do, but even after applying the correct amount of oil, I feel it will contaminate with time anyway.
I originally found my MAF contamination problem in the mid 90's the good old fashion way by trying to fix everything but, then I just happened to read a Forum post about the problems and bingo there was my fix. It took two years of using the K/N filter to contaminate the MAF but it was pretty badly contaminated when I found it and the drivability issues got pretty bad.
I am sure if you ask any tuneup mechanic that the first thing they check for when someone has drivability issues or suspect A/F problems, they take a look at the MAF.
You need to look real close for the contamination, a magnifiying glass in my case, but its very easy just to spray it away with the electronic cleaners like the CRC QD stuff.
I Hope these posts will save someone a trip to the dealer for this very easy fix. If you can change an air filter you certainly can check and clean a MAF on these GM motors.
Doug