86 Cavalier High idle

Hello, I have an '86 Cavalier with a 2.0. It idles high when started and doesn't idle down. It seems to idle even faster when it's warmed up. We've changed the computer and throttle position sensor. Still no
luck.I thought it might be a vacuum leak somewhere or a bad sensor that we haven't checked or replaced yet. Any ideas?
TIA!
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Could be a number of things - bad coolant or intake air temp sensor, vacuum leak, problem with the idle air control valve..
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Robert Hancock Saskatoon, SK, Canada
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Forgot to mention that the idle air was replaced too. I have no clue where the intake air temp sensor is. I looked on the intake manifold and didn't see anything that looked like a sensor. Looking in the wrong place or just over looking? Thanks for your reply.
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My guess would be it's in the intake air ducting to the air filter..
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Robert Hancock Saskatoon, SK, Canada
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The intake air ducting is just a plastic tube with nothing inside. The air filter sets on top of the throttle body. Wait..... there is a vacuum thing on the metal part of the air intake (for cold starts).
Well, we just started taking off the temp. plugs one at a time. When the one for the computer (I think) was unplugged the engine idled down . It was erratic and was puffing black smoke. When you plug it back in it starts idling high again. You think that sensor was the problem or would it do that anyway?
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wrote:

The Coolant Tempiture sensor/sending unit is on the bell housing side of the cylinder head, by the thermostat housing.
On the intake there should be the EST (Electric Spark Timing sensor) & the PULSAIR controller. Which has to do with the Smog Pump if so equipied.
If you unplugged the spark timing sensor, the engine shopuld run rich as timing is retarded. Charles
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The TBI unit is probably carboned up, blocking off the vaccume ports. Easy way to check is to pull the lines and check for vaccume. Then if you have vaccume trace each line down, looking for cracks, or splits.
If the problem was the same before and after TPS & IAC replacement, you could very well have wires that are dropping voltage. Cracked or worn insulation, broken strands, ect. Charles
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