Why does my grand marquis idle rough in park?
Asked by Guru9ZH2N1 Dec 08, 2020 at 12:14 PM about the 1988 Mercury Grand Marquis
Question type: Maintenance & Repair
Why does my my 1988 grand marquis idle rough in
park but acts fine when I press the gas
2 Answers
The basics for a rough idle, check for a leak of some kind, fuel--egr--vacuum. Check and clean anything that has to do with idle air system. Clean throttle bore and around throttle plate, see if it helps.
Guru9ZH2N1 answered 4 years ago
There is a vacuum leak but I cant find it, when I put it in park you can hear it, then goes away when I press the gas