Originally Posted by mpcv2000
Found this thread while trying to find answer about the exact same issue with my 01 Zetec Focus SE .
A/C no A/C is doesn't affect the issue but it is random and when it does the trouble , I get no DTC either but if I reset the battery the problem goes away for days if now week.
I don't want to change parts just for fun and the Original poster did change a bunch of things and he's having a similar issue.
In my case I'll have rough idle for a few days and after "0" idle.
I rest the battery and gone .
Any tips where to look at ?
Sounds like after resetting the computer it goes back to its base-line and then relearns a bad behaviour. I would clean and re"grease" your plug wires and especially any connectors to sensors that may have been replaced.
(Tom) out here might have some suggestions that would require capturing data while its running to maybe identify where the problem really is. Don't forget to check for codes that are in memory that don't light the MIL.