Accelerator sticks - not slowing down?

OK, So maybe I spoke too soon. The idle is fine, but when I take my foot off the gas when in gear going down the road, the car still doesn't slow down immediately like it should. It does start to slow down, but it really takes its time. I have a scan tool hooked up and am looking at the TPS reading and it goes back to 16.1% (closed throttle) when I let off the gas. There is no dead spots and it seems to read smoothly throughout the travel. I checked at parked idle closed throttle and it reads 16.1%. Is this normal? Shouldn't it read closer to 0%, as I have the throttle stop screw backed almost entirely out of the threads. I understand that when I put the TPS on, I have to tilt it into position and back down again so that the lobes mesh properly, so there may be a greater than 0% reading due to that. I just thought the ECM would adjust for that after an ECM reset and display a "corrected" % reading to show a more usable reading to the scan tool, but maybe not. Any ideas? I can't seem to find any other vacuum leaks that may cause the excessively slow return to closed throttle speeds. Thanks!

Steve, when I shift to neutral the RPMs pretty much stay the same immediately after throttle release, then begin to gradually drop slowly a few hundred RPMs, then they shoot back up for a couple-3 seconds before beginning the slow downward trend again as the car slows.

Ok, so I paid more attention to the "shift-to-neutral-while-in-gear-going-down-the-road-with-foot-off-the-gas-scenario". The RPMs actually do shoot up a 100-150 RPM immediately after shifting to neutral. This only happens when in the higher gears, though. When in first gear it is not evident -it is more responsive when in first gear. So on the way home I picked up a new TPS and tested it against the old one. The new one actually reads 18% throttle at idle vs the 16.1% on the old one. I went ahead and unplugged the IAC to see if it had any effect at idle, and it didn't have any effect until the load increased when the compressor turned on -then the engine started to stumble and run rough. I plugged it back in and then the idle got smooth again. I give up. I have absolutely no idea what to do next!

If in park pressing and releasing the gas has normal effect on RPMs. The RPMs drop immediately like a normal car does. It's only happening when in forward gears (reverse is kinda fast too, though now that I think about it). I'll check on the way home today to see if there is a difference when I have it out of Overdrive.

Steve, Is there something in particular that I can say to the mechanic at Ford to better explain what needs to be adjusted in the ECM when I take it in?

Thanks, will do. I will post the outcome for others to learn from.

While moving about 30 mph, my Taurus will slowly accelerate to 50 mph with my foot off the gas pedal on a level road. This is annoying in traffic because I frequently have to hit the brakes to slow down, and then it creeps back up.

Out of curiosity, I was moving at 15 mph in an empty parking lot and then put the transmission in neutral. The RPM jumped to 3500 without touching the gas. The RPM dropped to 1200 after I hit the brake pedal hard. I repeated this with the same results.

What's the scoop?

When the car comes to a full stop, the idle drops to normal. This would imply that neither the idle air control valve, TPS, MAF sensor nor the throttle linkage is involved. The idle will drop form 3500 to 1200 without the gas pedal moving.

As soon as the car is moving again (at as little as 10 mph), the process starts over again and the RPM climbs to 3500 in neutral (or the car accelerates when placed in drive). The RPM will only drop to idle at a full, dead stop.

Car starts and idles fine. When in drive, I get up to speed and release the gas peddle and the RPM's will not decrease. Car does eventually slow down, but only after miles of travel. I have actually traveled several miles at 45 miles an hour with no acceleration from me. Once I hit the brakes it will slow down, but it's almost like the gas peddle is always being pressed down a little, but only when I'm driving. If I'm stopped at a light, I will be idling at 800 rpms. But once I take my foot off the brake, RPMs will slowly climb up to 1500 rmps then shift into next gear.I haven't tried letting it go further than that. Although car was doing this already, I had a Check Engine Light with a code for the TPS, I replaced the TPS and reset code, light hasn't come back on yet.

Any clue?

I have the same problem but with a 1999 Taurus 3.0L
was told to replace the Idle Air Control Valve. Did but that did not help the problem. Next they tell me to replace the throttle position sensor.(Have not tried that yet). If I place mine in neutral the RPM's go up

Joe Thank's for the reply
No the check engine light has not come on and replacing the TPS did not change anything :(
Can't hear any vacuum leak but have no other way to check (far from being a pro on my part).

Ron