Okay, I have read through these threads for over a year trying different things to try to fix my issue. I have a 2005 Galant ES 2.4. It has a rough idle when sitting it drive at stop lights and drive through. (around 600 rpm) Some times it will go away for a minute if I shift to neutral or turn off the a/c but it will typically start again after about 30 sec. Fuel mileage seems to be a little less but not drastic, A while back the muffler did break at the end but I was able to reweld and I assumed it was from the age and rough idle? It can also take a bit longer to start than normal sometimes. Engine light will be off for a day or 2 sometimes longer but always come back on. Also SRS light is on but has been for about 5 years when the battery went dead the first time (was told that was normal and dealer had to reset every time battery dies?)

Things I have tried: replace egr (multiple times), replace 02 sensors (multiple times), replace spark plugs (multiple times) replace coils (recent) replace valve cover gasket (recent) replace injectors, clean, throttle body, run sea foam (though fuel and oil, and the intake cleaner) replace pcv valve, and replace upper cats (recent) check for vacuum leaks (multiple times), check battery and alternator output.

At this point I am at a lose and getting tired of throwing money at it. Other things on my list to try next where, lower cat, fuel pump, MAF sensor. Any ideas of what to do next would be very appreciated.

 

I talked to a different retired mechanic and he said either mass air flow or throttle body. So now they are both on order.... I will update with which one fixed the issue as they come in.

 

I installed a new MAF sensor and it has not solved the issue. Still waiting on the throttle body to show up to install to see if that helps the issue. I am now getting a P0154 code when about every other day.

 

Did you ever figure it out?