So when my 4 banger gets warm and I'm driving around town I'm having an issue with my idle, it will idle about 800 them drop to about 3-400 then back to 800 and keep fluctuating like its going to stall but it won't. It will also act like its going to bog down when I'm driving and hit the gas it feels like it hits an RPM rev limiter, and I get a loud popping/backfire kinda sound from the engine compartment, any ideas?? Iv replaced everything and I'm running out of ideas! I haven't done a compression check though, could it be a clogged exhaust system? I also have a fuel pressure of 55 psi at the rail with the vacuum tube on or off
This is what Iv replaced - TPS,IAC,Fuel filter, fuel regulator,cleaned injectors, oil change "came out normal" , air filter and cleaned my throttle body and new vacuum hose on fuel regulator and case vent.
I know my muffler is bad due to the chunks rattling around and I think my cat might be bad too?