Could just be throttle plate sticking--without engine running try to free with a screwdriver Could just be throttle plate sticking--without engine running try to free with a screwdriver
I found that putting low grade gas in car mad it idle high. Does it every time
On my Chevy truck it idles high when its low on antifreeze but if its not that more than likely its usually a vacuum line loose or cracked. good luck.
vacuum leak
see previous answers, but if it idles high it might be the Mass Airflow Sensor. if your car idles too high for too long and you keep driving it, you could burn out the transmission module (very expensive )
zyou tps might be bad
where is the i.a.c in a mercury muntaineer 2002
Year? Replace ECTS and clean the throttle body
throttle posistion sensor or vacuum leak
you might have pulled a vacuum hose off
Manual or automatic transmission?
depending on the year some impalas have 6 inch glasspacks
trash in carb or muffler stopping up.