1990 buick skylark fast idle and speedo prob

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Hello,
My name is John and I am new to this site.
I have been trying to research my problem and found this site.
I really could use some help.
I currently own a 1990 skylark with a 3.3 liter engine. About 87,000 miles on it. I would like to get this winter out of the car.
Recently when I start the car, either cold or hot, it starts with a very fast idle. I was thinking of replacing the IAC.
Yesterday the speedometer stops working at times, just drops to zero.
This am, I could feel the engine running rough when the Speedo stopped working. I plan on checking for vacuum leaks. I have removed the battery and alternator and both check out fine.
Any suggestions sure be appreciated.

I would also like to add. The car will travel about 40 mph on the highway when running in fast idle.
I took a late lunch today and the car ran fine. So this problem of mine comes and goes.
Lastly, this am when the car started in fast idle, I lifted the hood, removed a vacum line and the idle went below where it should be at. When I put the line back on, the car seeemd to run at normal idle again.

Thanks to all that reply in advance.

posted by  johnymac

Same 3.3 liter motor. I have already replaced the IAC, temp sender, battery, tested the alternator, and TPS. The tranny is new, new plug wires and plugs, as well as crank angle sensor and ignition module.

Now when it idles it runs at about 2,500 rpm, no way I would put it in gear with a fresh transmission. Did you problem get resolved? What was found to be the cause?

posted by  electrodes

I have this same problem on a 1990 Buick Skylark, 2.5L. Did you figure out a solution or cause? Thank you.

arsandov   15 Aug 2012 01:02

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