toyota avensis 1AZ engine p0172 error code

Am working on Toyota avensis and it's has no power.after i scanner i got p0172 system too rich bank 1.at that time oxygen sensor #1 and #2 was reporting rich condition always no matter how i accelerate(0.750 to 0.900 mv)LTFT -26 STFT -23)I started by checking fuel pressure with my scan tool which was reading between 7 to 10 mpa/psi 1500 i think so, at idle and i think that was ok.maf was reporting 26 to 30 grams per second and calculated load 100 % at idle which was wrong.after checking fuel pressure i check maf and i found it was so dirty and later replaced it.after replacement i solved almost 60 %of the RICH condition coz oxygen sensor bank I sensor started working rich and lean and also sensor 2 bank 1.STFT 1 to 15 and LTFT -8.NOW The car is running fine but backfires wen i accelerate from 800 rpm to 1300 rpm and from 1300 and above no hestation.no vocuum leak,no blockd fuel return line and all sparks are firing well.now let assume my fuel pump filter is dirty or some how blocked,can it make the car to run rich?i think it should be lean if the fuel pump or filter is blocked/dirty?friends how can i solve this problem?should i judge rich or lean condition by watching STFT Frustrating between +2 to 7 800 rpm,1500 rpm and above +5 to 17 LTFT -7 always?

Hey Cyrus! Nice catch on the MAF, never seen one of those overreport so badly at idle.

I'm familiar with the normal 1AZ, but they don't sell the direct injected version in the US Still, your fuel pressure sounds reasonable. The backfiring right off idle makes me think of a timing problem.

This is gonna sound absolutely crazy, but did anyone fill this tank with diesel? I've seen this before, contaminated fuel that'll allow the engine to run OK-ish under light load, but will fall on it's face under heavier loads.

I don't see a fuel filter problem causing a rich condition, unless the filter was installed on the return side (and they never are). If you saw your high side fuel pressure falling off during the backfire/cut out, then I'd say you're onto something.