I am at a loss. I bought a motor from jdm motors come from japan. After installing the motor would it would surge from 1000 rpm to 2000 rpm. I replaced the iacv tps checked for vacuum leaks and bleed the air out the coolant. Still same problem. I also swapped throttle bodys. If i plug off the vaccum to the iacv it runs fine no surge cel comes on of course for iacv. If i unplug tps surge stops. Any ideas on what to do

 

check the base idle by unplugging the iacv, idle should drop to 500-600ish, if not turn the idle adjust screw to get it down to that after making a mark to make sure you know where it originally was

if you can't get it down to that, then you have a vacuum leak that you need to find using either a fine spray mist of water or carb cleaner around the intake manifold with the car idling til the idle changes which means you found the leak

 

Thanks ill give it a try i sprayed all the vaccum line and intake with carb cleaner and could never get a change already so hopefully unplugging the iacv and adjusting idle helps. It start the rev issue if i shift over 3000rpm or rev it up