I hope I'm posting this in the right section, it's the first time iv ever posted anything in a forum! Iv got a 2wd saph cosworth that iv recently rebuilt engine on. Done about 600miles since the build, all going well until now. Engine won't drop below 1200rmp at tickover. Iv wound the idle air screw under the throttle butterfly all the way in and the throttle stop is wound all the way down so I no the throttles closing fully. The idle control valve isn't stuck because if I remove it but leave it plugged in you can see it move fully open then closed if you turn ignition on and off. If you unplug the valve whilst engines running it makes no difference to the idle, it stays at 1200. I suspected it to be a vacuum leak so checked all pipes ect and tried spraying carb cleaner round the manifold gaskets. If I spray it round the injector seals it raises the revs slightly which must mean it's drawing some in but I pit new o rings on them and it stil does slightly when you spray round them. Do u think this could be enough to cause the high tickover? I was wondering if the coolant temp sensor was faulty could that cause it to run on cold start all the time or would cold start use the idle control valve to raise revs therefore they shud drop to normal if I unplugged it?

Sorry about the long post, just trying to giv as much info as I can! Thanx for your time! Hopefully someone might be able to shed some light! Thanx. Ed