TownCar idle problems

1987 Lincoln TownCar

Automatic, 5.0

Used to stumble and sometimes stall at idle, usually while in gear. Sometimes in park.

Replaced plugs, wires, fuel filter, and idle air control valve. Serviced the throttle body.

The engine now races. Revs erratically while in park. Sometimes need to keep foot on brake to keep speed under 35mph.


The first thing I would wonder is whether or not you didn’t forget to restore or maybe disturbed a vacuum line connection when you did the other maintenance. I’d start there & look for open/broken/crossed vacuum connections.

I’d also double check the throttle body & linkage for any binding. Did you pull the throttle body? Check the gasket for that and IAC.

I’d then wonder about that IAC valve - was it just cleaned? New? Used? It could be sticking open.

In any case, it sounds a lot like an unmetered air problem.

Test the throttle position sensor, if it has one.