other possible problems.

[cameryfan92]

Just to be sure the fuel fillter is a potential problem i have a few questions.
The car sat for roughly4-5 months with over 3/4 of a tank of gas and a can of HEAT in the gas tank.
When the timing belt was first fixed the car started and iddled fine but know it starts to pop and crack after the engine gets warm, almost like a backfire but NOT.
When yo're going down the road it does the same thing, but not all the tim, just primairily at low speeds or in city driving.
when you rev the engine though it won't doit.(5000-6000RPM.)
This problem didn't develop until the car was started on a col morning, 10 degrees, and was idling real low with a BAD exaust leak.
I have added 3 cans of injecter cleaner and it seems to have helpped SOME but the problem is still there.
So what could it be?
Fouled plugs
dirty gas
bad fuel fillter.

P.S. the fuel fillter doesn't seem like its been replaced ever.