My car's idle was fluctuating between ~500-950 RPM when the engine was warmed up, and the A/C was turned on. In the end, I used the troubleshooting guide in Section F of the service manual to systematically diagnose the problem. When I started checking out the Idle Speed Control (ISV) solenoid at the back of the upper intake manifold, I noticed that one of the vacuum hoses back there was kinked. It was the hose that comes from the Switching Solenoid in the solenoid rack. The one with the check valve in it. After I had straightened it out, the engine idled fine, and ran smoother than it had been. The two lessons I learned; use the manual right from the start, and check all the vacuum hoses (twice!) when the engine isn't running right. Thanks to everyone who contributed to my original thread, and a big thank you to those of you who post your problems and final solutions to the forum!

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pedalpusher

 

hmm interesting thanks, i also got a hunting idle. Ill double check that hose and all hoses for it kinks. Thanks