Is this with the stock tb?
When I had this problem after switching to a pp tb I found this to cure my idle issues.
Right here is your issue...
it needs to read 0 or 0.4 with a flicker at 0.8 at the most
at 11% you will always be in the throttle follower table...which adds air, which causes high idle.
get the TPS back down to 0 and your problems will go away most likely
if the TB bump stop screw has been used to open the blade for idle air, then you need to test the voltage, again.. MUST BE LESS THAN 0.55volts
if you cant get it to idle with the voltage below the 0.55, then it needs more air and you have to drill a hole in the TB Blade
once you get the Voltage down, you must do a TPS reset
unplug TPS, turn key on for 10 seconds, turn off key, plug back in sensor, turn key on 10 seconds, turn key off, start the car.s
98 z28 vert
mti clear lid, hooker muffler, cutout, 180 thermo, pp tb, stb, all the freebies, lt's, ory, Kaltec tune, KYB AGX shocks,
mobile 1 full synth