Hi,
I have a 1.8 petrol that has had the head done twice and all the cooling replaced with the recommended modification for the thermostat location. It has done about another 10k since then but in the last few months has stared to idle at a high rate even when hot. When I rev it up, it will drop back to normal again. I can do a temp fix by resetting the idle rate - press the accelerator through the full range 5 times with the ignition on but not started but it tended to come back after a month or so.
This last time I have also cleaned out the Idle Air Control valve - it was black with a layer of fine soot and I used some air air intake cleaner for diesel cars that I had around the place with some tissue to clean up the valve.
Should I do anything else? It is running better again now but should I change anything else?
Thanks,
James