Ive searched and couldn't find an answer.

rebuilt motor, 1500 miles no problem, stock injectors, stock ECU, B16A2 in an 00 Si with a turbo kit - don't worry kids im not boosting just yet.

I recently had an STR 68mm TB that was on the car, but Ive decide to go back to stock because it was a pain in the *** to drive and made the pedal pressure feel horrible. I switch back about 10 days ago, no problems at all. I went to get gas the other night and when I started her up from getting gas I noticed a high idle around 1500 rpm. (keep in mind my TPS voltage is set to .48v at idle, so its within factory specs).

I go to pull away and i notice I cant rev past 1500, the car feels like it has a new rev limit. I have had a CEL, but thats cause the secondary O2 is unplugged. We checked the code and it was 14 and the one for the o2 (which I already knew about).

I mean its possible the IACV took a crap, but it seems odd. I haven't had any problems with the car, the idle has been great.

So i reset the ECU and it happened again and I did notice a lot of smoke, but thats cause the idle was high. I took off the IACV and the gasket looked fine, everything was flush against the intake manifold and it wasn't even dirty. I cleaned it even though it wasn't bad at all and bolted it backup, reset the ECU and its been okay. I turned on the A/C and tried to get the idle to get funny and give it gas which would cause the IACV to turn on (or something like that) and everything looks good.

Any suggestions why or anything that I could check that im missing?