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1987 420 SEL ...out of control IDLE Problem.....

04-02-2005, 03:44 AM

New to this forum..

Have a question.....I have an out of control Idle problem with my '87 420 SEL...when I first start it up, the idle goes up to about 18 and it stays there when in neutral, for at least 30 -40 minutes.. then finally drops down to 700, which is normal...going in and out of gears is bad for the transmission and the brakes when the idle is that high. I suspect it is one or both of the idle control valve etc? Can I replace both those units myself?...if so, how do I do it, or is there a book/manual that shows how to do it so I can save some money for a mechanic?

Thanks very much,


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