rpms do not drop between shifts?

[snkplssskin]

2001 p.p plenum and throttle body. ok i noticed when im going in between shifts the car does not drop in r.p.m like it should. when you come to a stop it will idle around 1 1/2 then it will decend to 1/2 where it should be. its really a pain when i need to stop in a hurry feels like the car is getting pushed until the rpms drop. now i did not touch anything on plenum or throttle because when i first installled everything it was mint. but thats when it was much cooler outside now the weather is getting warmer could that have anything to do with it?

 

[wmburns]

Likely that the TB idle set screw is set too high. This is allowing too much air to enter the TB. Remember that the IAC can only ADD air. So if the TB set screw is too high, the IAC can not control the idle as it should.

Suggest following the manf recommendations regarding establishing the set point. Optionally, monitor the IAC duty cycle. Should be between 40% and 60%.

Other things that can cause this is a bad TPS, Vacuum leak, loose/binding throttle linkage.

 

[ibn_inked]

I put an IAC restrictor plate on my 98 GT with PI motor swap at the advice of Stangnet members and BOOOM, hanging idle fixed! Got mine on ebay for less than 10 bucks.

Hope that helps!

 

[32ValveRom]

I had a similar issue with my 99 Cobra. Whenever my engine was warm enough I would come to a stop and the motor was still hangin around 2 thousand RPM. It would drop to 1 k a few seconds later but the issue made shifting gears a little bit harder.

The fix came when I did exactly what ibn_inked did. $10 and problem solved

 

[snkplssskin]

i seen a reply on here that a guy tried. ok pull off negative battery terminal,hold brake pedal for ten seconds re-connect terminal,let ac run for 5 mins and then the heat for 5 mins and reset clock,but my clock was not effected. now the car seems alot better, but i still get a little hang up but the difference is alot better. i also seen a threat on here about making your own iac plate, but im gonna wait a little bit just to see what happens.