I have a '99 Grand Marquis recently it started have problems at idle. Sometimes it idles but it feels like it is idling below its normal idle speed. When driving it doesn't have a problem at any speed, however, occasionally when cornering it will die. The check engine light has not come on (other than the normal times when starting or restarting). I had the codes checked anyway and as I expected I set a code of P1507 because I have been keeping my foot on the accelerator to keep it from dieing at idle. Any suggestions would be greatly appreciated.
'99 Mercury Grand Marquis Rough Idle/Stalls
Sep 11, 2005
3 Replies
IT sounds like tha IAC is dirty. Many times they can be cleaned and reinstalled after soaking in throttle body cleaner for a while followed by a good spray dousing. While you are at it, it would be a good idea to clean the MAF sensor and the EGR ports in the manifold. The IAC will not normally set a fault code just because it is dirty. It can also cause hard cold starts and no high idle when cold as it should be.
Lugnut
IAC valve.
Almost 100% sure. May be crapped up, may be shot. Just had exact same thing last week on my Vette. Ran rough for a long time before it gave out. Pintle all carboned up.
-GeorgeC
Im with these guys, had to clean it on my 98 CV and my 2000 GM.
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