Putting, chugging, and stuttering in park - need some advice here

[_-DZ-_]

My friend (who knows nothing of the underside of the hood) owns a 92 grand marquis. It has pretty high milage - but the previous owner drove it like a sunday driver.

now for the problem--

Recently it has had a stalling problem. When its started up it seems to run fine, but shortly afterward the idle seems to lessen and the car spits and sputters. The odd thing (to me) is that this only happens while it is in park. The second you put it in gear it idles up and runs fine. Recently i replaced the spark plugs and wires on it, but the problem did not start untill a few weeks afterward, i figured the problem was unrelated. also, the dummy light (check engine) will breifly come on and off again. if anyone out there has any ideas of the problems origin - i would be very greatful.

thank you

[Samurai0]

This must be either a special MGM problem, or more likely a problem with Hi mileage.

My '87 is the same way. Starts, idles well, then slowly drops off and feels like it's gonna sputter out (sometimes it does), without gunning the accelerator pedal.

When I shift into gear, it runs great.

[89Tank]

Have a mechanic check the operation of your EGR (Exhaust Gas Recirculation) Valve. When the car is in park and at idle the valve should be closed. When the car is being driven the valve opens and recirculates your exhaust gasses. Hense the name... This can effect idle and stalling issues. There might be some carbon build in there.

There is something else you can check. Very simple. Take a look at your throttle body. After time carbon builds up on and around the throttle plate.
Just use a clean shop rag and some carb cleaner to clean it out. *tip* place a rag underneath the throttle body to soak up the carb cleaner.

I hope this will help you out.

[cobradude360]

i have a 92 ls my self and 1st would try replaceing the spark plus and wires also clean the throttle body and make sure that theres no vacum lines cut or disconected and finally that big oll black thinf that is connecting the air box and the throttle body needs to be put on exactly right the rubber needs to go around the black part and then connect it to the throttle body hope this helps.