just as the title states, start the car when it's cold, runs well, (low operating temps) once the car heats up, it starts backfiring. I'm thinking it might be sensor related and could be triggered by going closed loop.

Also noticed this morning that it ran well while it was still chilly outside (70 ish degrees) if it gets into the upper 80's + then things go to hell...So, what do you guys think it is? Thanks in advance.

 

sounds like the air fuel ratio's out ? check codes first then report back ?
they dont use o2 sensor on open loop do they ? its a start....

 

only code that comes up is 24 - No Speed Signal (4th gen dash that has never been finished = computer not knowing how fast i go)

O2 sensor isn't used in open loop i believe....

rebuilt the vac hoses, checked MAF (had many issues w/ it b4) and still need to tune.

Also, mid throttle is very boggy, (when hot , both water temp and actually outside temp), that's where she'll typically start to backfire....Unplugged EGR hoping it was just sticking open, but, problem still occurs w/o it.

 

if its running fine cold not using o2 then when its warm crappy and uses o2 to read mixture....... that is what i was thinking,
another problem of bogging could be clogged cat, both these are quick and easy to check

 

Most often it an exhaust leak at the header or y pipe, once warm, the leak suck in air that mixes with unburnt fuel and the heat of the exhaust lights it off.