Need help with warm idle loping

[Dave...]

Hello All,

I am new here and looking for some help. I have a 1993 Mercury Sable Wagon (sorry, not a SHO, but still need help). It has the 3.8L engine.

Here's my problem. Car starts and runs just fine. Gets 17 mpg in town and 20+ mpg on the road. The Engine warning light is off and does not flash.

Idle is fine when cold. After warming up, the idle is still fine when in gear (750 per the tack).

BUT, when I shift into neutral (auto trans) the idle goes to 1,000, and drops to 500 RPM every 3 to 5 seconds, shutters / lopes then back to 1,000 rpm.

This is a new problem and getting worse. Can you please help me with what to check?

Regards,
Dave

 

[Mr Anonymous]

Try http://www.tauruscarclub.com there's more regular Taurus and Sable types over there...

 

[Dave...]

Thanks for the link.

Just to clarify, I am not really a Taurus Sable type. My Dad passed away and this car will be going up for sale when I get it fixed.

Does anyone else have input on the idle issue?

Regards,
Dave

 

[SHOZ123]

Either a vacuum leak or a bad IAC valve