Subaru Repair: Engine Stalling, mass air flow sensor, mass air flow

Question
I have a 2000 AT impreza 2.5RS. Just recently I had it bring up a CEL. I didn't have a chance to get the code checked and it was on for about a day and a half, then I went to start it up and the light was out, but then after a bit of driving the engine would start to hesitate and act like it was going to stall, and would almost stall (example, very rough idle at stop light, when putting on gas would act like it was going to stall, but pick up and go just fine) - so, idle stalls out, gas, runs fine. Any idea on where I can start to trouble shoot this? No CEL to check for codes, could it be O2 sensor, vacuum leak, etc.? Thanks.

Answer
Most likely Mass Air Flow sensor.But having said that it needs to be diagnosed.Dont assume that whatever code is pulled from memory indicates a failure with that circuit or componet.And remember a check engine light is telling you that you have an emmissions system or emmisions system monitor failure and could be potentally excessively polluting our environment.So the proper diagnoses isnt just important to your symtoms its important for the health of our environment.

Justin
All Wheel Drive Auto