Possible MAF problem on 99 Grand Prix ?

no it would set a code if it was, u sure its running rich and how rough could be spark plugs if they are cracked slightly it may only run like that when u get the car warm and that would explain the rich running bc there will be unburnt gas, also could be one of the 3 coils try to get a good clear video of what its doing. im ASE certified so im not gonna give u a bunch of bs answers i went to lincoln tech grad with a 3.5 neways get the video and check the engine temp

There is a part under the front passengers side fender above the wheel well Called a fuel pump resistor. If that goes bad as it did with me you can Keep the car running if the rpms are kept high. Just go to the nearest Parts store ask for a fuel pump resistor. It's a circle or oval ceramic resistor With a plug coming out of one side. But that is the problem. Don't mess Around screwing with all the made up stuff from twenty thousand certified Mechanics. I have the exact same car and it did the exact same thing And that particular part was the only electrical sensor I had NOT replaced Good luck man