how can one hard acceleration cause 1997 Taurus to idle VERY HIGH ever since

My car (1997 Taurus GL 3.0 V6) was running rough one day and I pressed the gas pedal as far down as it would possibly go while accelerating from a dead stop. I performed this hard acceleration for about 75 feet and then I let off the gas pedal. EVERY SINCE THEN MY 1997 Taurus GL idles EXTREMELY HIGH in Park or Neutral...instead of idling around 800 rpm it now idles around 1900 rpm. Sometimes the idle will finally quiet down to around 1400 rpm. Any possible ideas? I sprayed starting fluid in the general area of the vacuum lines but no change in the engine rpm.

Another interesting fact: I have the cover off from the area above the engine that covers the gas pedal link, and the return spring for the gas pedal link. If I barely move the gas pedal link with my hand...AND I MEAN ABOUT 1/32"...the rpm's IMMEDIATELY jump to 2000 rpm or more. The rpm's eventually fall back to about 1400 after about 30 seconds.

I have installed a new IAC and that did nothing to fixing this problem.

I connected my scan code tool to my car and the TPS voltage is at .85 volts when the gas pedal has been released.
What should the TPS voltage read at PROPER idle for a 1997 Taurus GL 3.0 V6?

What should I try next?

(ps - the rough idle has been fixed since the high idle...bad spark plug for cylinder #2)

I'd suggest that you get a can or two of throttle body cleaner, remove the intake air tube from the throttle body, open the throttle plate all the way, then spray the back side of the throttle plate and the throttle body bore with the cleaner. It sounds like you have a build up of sludge in the throttle body and probably on the back side of the throttle plate that is preventing the throttle from being able to fully close.

A couple words of caution: 1) The engine will be very hard to start after spraying all the cleaner in the engine. Ideally you would remove all spark plugs, put rags to cover the plug holes, then crank the engine for a few seconds to purge most of the liquid out, and 2) The throttle plate will probably work much more freely after the cleaning which means you may over accelerate the first few times you drive the car. If backing out of a small garage or in to the street immediately after this you'll want to keep this in mind.

-Rod

I will be cleaning the throttle body tomorrow and checking for vacuum leaks. I will post my results.

I checked for vacuum leaks and found none. I cleaned the TPS and it was nice and clean to begin with. I took out the original PCV and the bottom was completely gone!!!! I replaced the PCV and the car idles perfect.

Interesting, thank you for posting what you found. I'm glad to hear you got the issue fixed!

-Rod