'91 Grand marquis 5.0 liter

1991 MERCURY MARQUIS
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NK972003
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  • 1 POST
I have a '91 Grand Marquis and when i turn on my car there are 1 or 2 surges in rpm and then it cuts out unless I hit the accelerator immediatly. After that it runs fine until I have to stop at a light or slow down and then it cuts out again. I had this problem before except it only happened when I ran the AC or heat but it would only surge and not cut out. ( by the way AC does not coo if that helps) I had a major tune up about a month ago and put in concentrated fuel treatment but it still happens.
Any help would be great.

Thanks,
Nikki
Dec 10, 2006 at 3:02 PM
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MERLIN2021
  • ✓Experienced Mechanic
  • 17,250 POSTS
surges are caused by vacuum leaks. Get a can of spray gumout, start the car, or have someone else do it and spray around vac hosoes and the corners of the intake manidold, when a change in RPM occurs you are in the right place. 5.0 engines have a problem with the aluminum intakes disolving at the corners! Also were the PCV plugs in at the back , top middle of the intake, the rubber bushing becomes brittle. This cauases oil and air leaks!
Mar 5, 2007 at 10:59 AM
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