Are you talking about setting the TPS? Or the idle stop?
If you haven't removed the stocker, unplug the IAC, (and Iguess the TPS) and see where it idles. Put the new one on, and set it for that same idle speed. Plug in the IAC and TPS, and set the TPS to .98 volts with the engine off and the key to "run", and see how it runs.
I'm not sure if this is the right way, but it's what I would do.
__________________ 1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads! | 
1990 mustang help with new throttle body install 
