88 Camaro 2.8L V6 hesitation, back-firing during acceleration

I'm having problems that started recently. I have replaced the wires, plugs, cap, rotor, and fuel filter. All these actions have improved the response of
the car but have not solved the overall problem. I have checked for trouble codes - none. There are no exhaust leaks. When the car is cold, sometimes takes time to start, and you can smell gas form the engine compartment. This I found odd because it is fuel injected. It also can hesitate before it revs up but when in gear will accelerate readily with sometimes a backfire from about the area of the cat but its peppy enough. BTW it is MPFI. The problem is once it warms up it will adjust the timing through the ECM and when you accellerate it will sputter and miss, back-firing until you back-off the pedal and try again where it will either go OK or do the same. It can also run fine if you apply steady slow acceleration. Then again it can react as if nothing is wrong and accelerate through the gears without a problem. When you are driving along at high speed it seems to run without problem, good acceleration and high end. At idle, running temperature, you can hear the engine change rpm's. When it is at a higher idle there is no miss and it rev's fine. At the lower rpm you get the hesitation in response to the throttle change. I am going to do the compression test on the cylinders next, but it seem to me that it would be constant through all circumstances if I had a flat lobe or sticking lifter. Any suggestions out there?
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Have you checked/cleaned/tested the Mass air flow (MAF) sensor? Common issue on these.
If you used a cheap air filter, the fine dust will settle on the hot wire and cause it to insulate and it will cause some of the problems you described.
Good place to start barring that all other stuff is in order. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going.... '91 S10 Blazer 4.3Z
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I've got the same problem with my '89 Firebird 2.8L V6... only my backfiring happens in deceleration. Not the mass airflow, tps, idle air, filters (air, fuel), or even the decel valve. all new from dealer. It's not even the timing, or the distributor itself (yes I replaced that damn thing too).
The curious thing is.... when you force it into "limp mode" your power and all that sucks... but it doesn't hesitate, or backfire. So to me the engine is normally running rich, but it's not even the injectors, or it would run rich in limp mode too.
Anyone have the not-so-obvious.... although correct answer... that it's the MAF?
'89 Pontiac Firebird Red 2.8L V6 MPFI

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What year do you want? I-4 or V6 SE or GT?
What flywheel did you use when you went to a 3.8 for a 2.8? I plan to do this to a J-Body soon. Charles
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