Hello I have a 1992 that I just finished turboing. I have a DIYPNP ECU and the idle keeps fluctuating between 300 and 1500 rpm. It seems like there’s a vacuum leak, but I cannot for the life of me find it. I’ve looked everywhere. The car was doing this a couple of weeks ago, and I installed the Idle speed control valve into the intake piping and that fixed it. A could days later it started doing it again. Sometimes the car isles at 400 rpm but I can not replicate it. Any help would be greatly appreciated. Here is the data log of it idling. Also, I am trying to set up 2-step, however when I jumped pins 1v to input2 in, and input2 out to flex, and turned it on in tuner studio, nothing happened. It is a 92 that came with cruise control, so I read that I had to unplug the neutral safety switch, but that did not change anything. It does not work in gear or in neutral.

 

Don't worry about the idle. Once the two step is working the turbo and engine will be damaged pretty quickly. Buy fireworks if you want fireworks. Race teams using two step replace the turbos and rebuild engines every couple hundred miles, and not because they enjoy disassembling things and spending money.