My '86 CS LX wagon has a tad over 88K real miles on it, and has been a local car all its life. Normal set-up with a bone-stock original 5.0L. Car runs down the highway very well. BUT, at a cold start, it can take about 4 - 5 seconds for the car to start. At cold idle, it goes way low in the RPM range (I estimate 450 or so) then it'll zip up to close to two grand in a steady rhythmic effect. Once warm, idle is now close to two grand and 45 mph! If I shut the car off then restart it, it'll go back to a normal idle; but then the problem recurs in a few short moments. I have replaced the cold idle solenoid that mounts at the back of the air plenum, near the throttle body opening, and that helped a little. I pulled in in the garage yesterday and the idle dropped to to stall while in Drive. WTF? To me, this sounds like a sensor somewhere is tits-up. I love driving this wagon, but with the idle and driveability problems, it's gonna sit in the garage until I can sort things out... Any ideas???
Do a KOEO code pull. I posted the procedure in a thread on someone's Ford wagon, along with the code lists. This'll tell you if there's one or more codes in Continuous Memory, which is displayed after the KOEO test (and it can also yield one or more codes of the things it tests).
This page: http://www.stationwagonforums.com/forums/threads/ford-ltd-crown-victoria-diagnostics.40405/page-2 and go down to post #24.
