Sounds like you did all the typical fixes for the problem you are having. A high
idle can mean a vacuum leak. A vacuum leak can also cause the engine to
burn rich.
This simple test might reveal the source of a vacuum leak. With the engine
idling take a can of starter fluid and spray around any suspect places of
vacuum leak on the engine. If you find a spot where you get an increase in RPM
you found the leak. If this doesn't reveal anything try the following vacuum
diagnostic.
Here is a good reference for vacuum trouble shooting.......... You should get
between 17-22 in. hg. depending on your elevation above 2000 feet MSL or
mean sea level. To perform this test hook vacuum gauge directly to manifold
vacuum. 1. Low steady needle usually indicates leaky intake, a leaky vacuum
hose, late timing, or incorrect camshaft timing. 2. If reading is 3-8 inches low
and fluctuates at that low reading suspect an intake manifold gasket leak at
intake port or faulty injector. 3. If the needle has regular drops of about 2-4 in
hg. at a steady rate the valves are probably leaking. (Perform a compression
check). 4. An irregular drop or down flick of the needle can be caused by a
sticking valve or an ignition misfire. 5. A rapid vibration of about four in hg.
indicates worn valve guides. 6. Slight fluctuation of one inch or so indicates
ignition problems. 7. Large fluctuation perform a compression check. 8. If
needle moves slowly through a wide range check for PCV issues. Hope this
gives you a good place to start and helps you figure it out.
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