hi, i have a ford focus 2001 1.8 petrol and i have been having a few issues with it for a while. To start with i had trouble starting, the engine would turn over but it wouldn't fire. I found that if i hold down the throttle while trying to start it would eventually fire and it would run fine. after a while i had issues where after starting, the engine would only keep running if i held the throttle down. from doing a bit of research i figured this was due to the IAC valve which i replaced (my cousin got me a new gasket and i got the valve from a breakers yard (i cleaned the valve with carb cleaner before i put it on)). this completely solved the starting problem but now when i am coming to a stop and i disengage the clutch the revs drop right down (to like 400 - 500 rpm or something), sometimes the revs just jump back up again and sometimes it just stalls (quite inconvenient when coming up to a roundabout).
could this be down to the IAC valve i got being bad? could i have created an air leak? or could it be something unrelated?
Thanks for reading