I recently installed and match ported a 65mm throttle body with a core exchange. I noticed immediately in traffic that my idle was hanging at 1800 then drop to 850 and back up. I got home looked for any loose vacuum lines and decided to close the BISS, this seemed to cure the problem for a few days. But yesterday, while in traffic, the idle was stuck at 1500.

Thinking I may have gotten a bad IAC, I swapped it out with a low mileage one, reset the ecu and so far so good... right?

Well, I'm not so sure after logging the car. The ISC Stepper values look high compared to others I have seen and my Fuel Trim Low looks completely out of place.

I'm going to back off on the BISS and see if it changes anything. Any thoughts? How do these look??