My 20 02 Expedition has 190,000 miles. It has been a good vehicle other than 2 fuel pump replacements. Idle normally 600 rpm. Last couple of days Idle oscillated up to 1200 and down to 500. When put in gear it was surging to 2000, with associated lunging.
checked for Vac leaks none noted. Cleaned the IAC Seams to have resolved the problem