What cause backfire out throttle body everything is brand new from fuel pump to sparplugs all sensors an coilpacks

What is your question?

Car sat for years had bad fuel pump drained gas replaced pump and fuel filter car ran 3 days shut off started back moved on carport it backfired out intake wouldn't start replaced plugs wires both coilpacks crank sensor cam sensor maf sensor added new gas and little fuel treatment and car is still backfiring out throttle body it will try to start then backfire and just crank it does this repeatedly exchanged all parts again still doing same thing checked timing chain everything is dead on checked for vaccum leaks replaced all hoses no change I'm lost and it has no codes at all

What makes this problem better or worse?

It doesn't change tried when warm & cold

How long has your 1996 Mercury Grand Marquis had this problem?

About a week