Rough Idle - KOER Codes 21, 41, 91
One fine weekend I decided to clean my IAB & TB and change my plugs (.54 gap) as I've done in the past. Well, decided to also clean my MAF and gunk in the EGR while I was at it. After doing this stuff, my car would no longer start cold and stay running without me tapping the gas. After the car warms up for a couple mins, the car idles at around 1000-1200 RPMs. If the car sits for a couple more mins the idle drops to around 700 and the car shudders. I never had this problem before. I could always count on the car to start and idle smoothly on the 2nd turn of the key (1st one would always die).
Also related...when at a traffic light the car will stop and idle at 900-1000 RPMs, then after a minute or so of sitting idle at the light, the car will drop 200 RPMs and start shuddering again! Then when I try to leave the light I get a slight hesitation when I hit the gas. The car pulls harder since cleaning the MAF at WOT...why does it develop problems sitting at idle? It used to be very smooth before I cleaned stuff and changed the plugs.
I had no KOEO codes, so I ran KOER codes and got 12, 21, 41, and 91 after heating up the O2's for 2 mins. I have checked my TPS, I have replaced the ECT sensor, and tried resetting the computer after each change. I checked all vacuum lines to see if they were all connected snugly and as far as I can tell there isn't any leaks (haven't tested). Next, I plan to have the fuel filter changed and then I will swap out the O2 sensors. Is this the right approach?
Reef Blue 1993 5.0L Coupe - AOD w/ Baumann Shift Kit, 3.73 Gears, MoSport Pulleys, 2.5" Flowmasters, Subframes, Eibach Springs, Steeda Camber Plates, ADS Computer Chip, K&N