My 1.8 Focus has had a rough idle for a while now, it seems it wants to stall, but then it revs itself a little to stop it from stalling and repeats over and over, if that makes sence.
I have just today fitted my 2.0 port and polished head with piper cams and vernier pulleys, along with a new inlet manifold and throttle body, cam belts and tensioners, aux belt and tensioners, oil change and filter and thermostat, so near enough a full top end rebuild.
I know the cams will make the idle a bit rougher, but when i 1st start it, its idles nicely for 20-30 seconds...then it starts to go rough.
Im thinking and have read it could be faulty mass airflow sensor or idle controll valve, and to check vacuum hoses and change fuel filter.
The idle controll valve was new with the inlet manifold, so its not that.
Any ideas pleaseeeee help!
Thanks
Joe