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First thing I would do is check for vacuum leaks, especially around the intake tunnel downstream of the air meter. Are the rubber hoses for the flame trap intact? Look around the oil separator. They can dry out and crack, even the oil separator can dry out and crack. The next thing to check is the idle motor, it can get gunked up and cause it to chase the right setting and never actually find it. Check the foil air tube that runs from the exhaust side into the air filter box, there is a valve that should close after warm up to keep the air from coming in from over the exhaust manifold. This can lead to burned out mass meters.
When my intake manifold failed, it caused a lean condition and the car did not run very well when cold, but ran real well when hot, it just had a steady miss at idle.
I also had a code 113 and 115 that I drove on for a while while trying to cure, after a month or two then I got a code for the air mass meter. I am not really sure how I fixed all of the codes, but they all corrected when I disconnected the big plug and cleaned and bent the contact points in the plugs. It is located on the driver side wheel hump under the hood.
I also had hard hot starts for a period when the fuel regulator failed and was drawing gas into the vacuum line.
Do you think there were any other codes stored? Usually if the engine is hunting for the correct idle speed I would think there would be some codes for long term and short term fuel trims.
Another thought is the coolant sensor, if it is showing that the engine is always cold when it is not, this would make all of the setting too rich. That could affect idle speed.
Hope this helps.
DanR 94 964 235,000 miles
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DanR
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