i would think if its a vaccum lines it would idle really rough all the time.Mine was running fine all the time then just lost power and then it would stall out.I recleaned the MAF a couple of weeks ago with mouth wash and all is well.A buddy of mine who is a GM tech said forget the MAF cleaner at the parts store just use some scope mouth wash and it made it nice and shinny.So we will see.I have my fingers crossed this was it.