idle incorrect after motion

[phenomena]

Alright folks here we go.My 86 shelby has been upgraded to a 88 system,the engine completely redone.Here is my list then i will pose my problem.steel crank, t2 rods, forged pistons, file fit rings, 1mm over valves,ported exhaust,3in down pipe,46\63 turbo,spearco intercooler,40 over injectors,programmed comp,12psi boost,12 degree timing,60psi fuel pressure.The car starts cold with a fast idle then falls to 1100.that is great til i drive it, when the speed sensor triggers the idle rises to 1800.After i stop the car wont come down to normal unless the ac is on.I can restart the car and the idle is fine til motion.Is this in the computer? Please help with the last issue i have

[NAJ]

Without a scanner it will be hard to tell but it sounds as though the controller is not seeing or responding to a decel condition. Connecting a scanner and veiwing all data input will lead you to the problem.
With all of the changes did you check to be sure base idle was correct and did you reset AIS?
When you accelerate the controller assumes you will eventually come to a stop, in response to this the controller commands the AIS to "step out", usually to about 40 steps in anticipation of a stop or release of throttle so it will be ready and a stalling condition will not arise. If the controller does not recognize the release of throttle the AIS will stay at its decel position.
The controller will look at numerous inputs including Map vacuum/TPS voltage, VSS input,etc.

[phenomena]

i set the throttle as low as i could get it without it sticking,i will check it with the scanner monday and reply

[NAJ]

Pay close attention to AIS steps.
The controller does not really know where the AIS actually is, it assumes it is at the correct position when it commands it to move.
Idle in park/neutral should be 10 - 15 steps, it will move out when load is applied or throttle is increased while moving.
With a scanner you can go to minimum air flow which will command the AIS to step all the way in to 0 steps which will allow you to check base idle and will reset the AIS.

[vxvxandrewxvxv]

SPEED DISTANCE SENSOR. It tells the engine how to idle when in motion. Especially in decel. you should also set your base idle. search for the steps there here somewhere.

when you did the engine/electronics conversion, did you go to the new sensor?

[FastByDesign]

You said +40's with 60 psi fuel pressure that's way too high....do you have a adjustable fpr? it should be set somewhere around 23psi i think... stockers flow about 28.05pph at 55psi. the +40's flow about 28.50pph at 23psi but at 55 psi they flow about 44.05pph. It could be why your idle is high.....this may not be the problem but i thought i'd throw it out there. If i'm wrong please correct me guys, i'm still learning this stuff.

[phenomena]

I appreciate the input fellas.I have been busy at the shop for a nice change,so it may take a few days.I will relearn the ais then set the minimum air rate.My oxygen sensor reads 88 at 60 psi fuel.Idont want a lean condition.I do have afpr.I did not update the speed sensor.Thanks again to all!!!

[phenomena]

I did it guys!!Here is what I found.The job took 2 quiet hours at the shop this evening.I had the polarity reversed on the iac.The modis,shopkey,and the old handy 88-90 chilton driveability ford and chrysler manual all showed different pinout info.Anyway the modis did not display iac counts so I took the iac off,pulled it out set the minimum air rate at 640 and now have a sweet 950. Thanks for the help again!!!!!!!!