Pontiac Problems? Ask a Mechanic for Answers ASAP
Hello and thank you for your question,Can you tell me what the actual codes are that you are getting?Dose the engine run okay once its running?
Providing you fuel pressure is okay and you are sure there are no vacuum leaks I would try disconnecting the negative battery cable and after doing so, give the MAF (mass air flow sensor) a good cleaning with some MAF cleaner and see if this resolves the back firing concern. Give this a try and let me know the results and we can work from there if need be.