Low idle and engine cutout

[fordnmerc]

On my '86 Grand Marquis with apparently 40k original miles, it will start right up immediately when cold and then within a short time the idle is low / running rough and then the engine shuts right off. I just replaced the IAC today and it made no difference at all.

When this happens, you can start it right back up again immediately with no problem and then the cycle begins all over until the engine shuts off again.

Ideas? Thanks.

[miamibob]

Did you clean the ports the IAC attaches into and in addition the TB?? Have had some goofy results with non0OEM parts so use Motorcraft for the IAC, TPS, etc...

[nfldfordltd]

Has the car been sitting for a while?
I park my 88 Town Car every year from November to May, and when I first start it in the spring, it does the same thing. Sometimes only for a day or two, other times for over a week but it always straightens itself up on it's own once it starts getting used more frequently.
It may just need an idle screw adjustment to get it sorted out.

[fordnmerc]

Thanks....I will check these things out when the weather is not so hot. We've had a lot of heat and humidity here lately.

And yes, the car was doing a lot of sitting before I got it.