My 93 LX 5.0 with 130k miles on it has been idling poor lately. Stalls out after first start-up and idles very rough after. Did a tune-up, cleaned IAC valve, throttle body, air filter and inlet. No change in performance.
Ran KOEO test 2 times.
1st time i let the car warm up a few minutes and got:
24 (Intake Air charge temp sensor or vane air temp sensor out of range)
81 (Air Diverter solenoid fault, intake air control circuit faul, air injection diverter)
34 (EGR valve not opening properly)
10 (finish code)
2nd time after a longer warm up (10 minutes after running first KOEO test) I got codes:
1. Would not letting the car warm up enough give you code 24 & 81
If you are still getting code 34 check and see if the EGR valve is holding vacuum as well as the vacuum lines to the EGR valve.
I reused my original EGR valve because it is in good condition however the Standard Motor Products EGR position sensor I bought came with a thin pos rubber o-ring that does not fit the sensor properly.
Even with the o-ring positioned properly it caused a vacuum leak in the EGR valve.
I reused the original Ford o-ring gasket that fits perfectly and causes no vacuum leak in the EGR valve.
Something to watch out for and I think I read some aftermarket EGR valves are of poor quality and if it doesn't seal at idle it will idle like crap.
Did you disconnect the battery to erase the codes after installing the new parts?