1990 Merc Sable 3.8 has a high idle problem. when you turn the key it idles at 1700rpm and when driven it'll go up to 2200rpm and 45mph without my foot on the gas pedal. not driving it now..too dangerous.

Any ideas why it's doing that?? is it the EGR valve?? THANKS

You likely have an intake manifold air leak or a vacuum line is off.

most likely it is the IAC motor or the idle air control motor it is located near or on the throttle body and is round with a two wire conector try smacking it with a hammer good luck