If the PCM is replaced, it has to be programmed with Ford Service Function Card and NGS Flash Cable so you would need to send it to the dealer.
When idling is irregular, the most common fault would be the IAC but during driving, the MAF would be the more likely cause. Was the MAF replaced new or used and is problem exactly the same as before replacement or are there any changes?
Other things to look for would be vacmun leakages that occurs only at higher engine speeds. Maybe some solenoid valves that are activated are faulty resulting in vacumn leakages.
Should not be the CKP but possible to be the EGR vacumn side.
Friday, August 13th, 2010 AT 6:49 AM