Recently, i had a "Check Engine" light on. I had it scanned and it came out to be P0101 which i was told is the MAF sensor. I have a friend mechanic who works for GM and he has the Tech2 scanner. He checked the MAF of the car if it's functioning and according to the data and I actually saw it, the MAF is sensing as it should. But even though it's sensing after clearing the codes, I still have the usual symptoms of stalling when at a stop, and intermittent loss of power. Aside from the P0101 code, i also had P0175 and P0172 which was interpreted as rich mixture in bank 1 and 2. In short, the oxygen sensors are sensing a rich mixture. Now, my friends interpretation is that even though the MAF is actually functioning, and since the ECU is reacting to whatever is reported by the MAF, he said that probably, there is initially a lean mixture of gas and air, and of course the ECU will try to balance this and so there will be more fuel injected. Now, he said that the Fuel Filter could be clogged that is why initially, even though there are attempts to inject more fuel there isn't and then the ECU will continue to command the system to inject more and there will be instances where it will inject too much thus the "rich mixture" report by the oxygen sensors. Since we saw that the MAF is functioning, it should be okay even though the code is about the MAF. Is it possible for this to happen? Normally, when the MAF goes bad the code is P0100, mine was P0101. Is there any significance to the difference in the code? Could the observation of my friend be possible. At any rate, I will replace the fuel filter and see if it improves or solve the problem. I added a fuel system cleaner just recently because i thought that it might help a little bit (actually used the one made by Chevron). But the symptoms still persist. Any input will be much appreciated.