I have A 1993 Bonneville ssei (3800 supercharged) it has a throttle body and supercharger off a 1995 (larger TB ). everything has been fine for a couple years till recently...
When accelerating it wants to hesitate badly and the check engine light comes on, code come up for the MAS intermittently some times it does sometimes it dont ... The part number is AFH50M-03A
So I tried to replace it with the MAS off the 95 that I had from the TB+SC swap #AFH50M-02E, car will not idle and dies (according to GM the 92-96 MAS'* are all the same)..
So I did some reading and read several discussions where it is recommended to clean the MAS with cleaner (CRC mas cleaner) which I did (03A)...It worked ok for a day or so then boom hesitation and check engine light and same code again..
So I purchased a MAS thru a local parts house (BWD) and installed it and it will not idle (surges and dies) and will not fast idle when cold (choke) which is the same symptoms as the 02E sensor.
So to summarize the 03A mas will idle and choke perfectly but has intermediate acceleration issues and pops the check engine light, and the 02E and new MAS will not idle or choke but seems to drive and accelerate fine and doesn't seem to pop the check engine light (50-75 miles worth of driving)...