My car is almost ready for dyno day, I'm going to install new spark plugs and change the oil to rotella before the day, oct 15. Installed a full gates racing timing belt kit testerday. Decided to keep the stock down pipe for now, just to keep a cat and noise level down. I installed a borla hush, perrin turbo inlet and upgraded the fuel pump flow with a walbro 255. Everything is working well except for when I'm rolling down to stop, idle dips to very low rps as if to stall out but when I come to fully stoped it actually bounces to normal idle. When I start the car idle is perfectly normal, it only dips low when I'm slowing down to bring the car to a stop. After stoped in a second or two it just bounces to normal idle. Once its idling normally, if I step on the gas pedal very softly and rpms beging to climb, it gets ruff at arround 1000 rpm and then it recovers to normal quickly. I cleaned the idle control, installed it and the check engine light came on, engine stalled and wouldnt start again. After replacing the idle control from my old engine the engine started and check engine light is gone. The unusual idle situation didn't change by replacing the idle control. The interesting thing is that the problem only occurs with the jdm ecu, the car idles to stop perfectly with the usdm ecu. Swap the jdm ecu back on and problem returns, swap usdm ecu back and problem is gone, jdm ecu goes back on, slowing down idle problem comes back. I do have the plug under the throttle body disconnected. No matter what I have done or changed the problem is there, but not with the usdm ecu. I will be using the jdm ecu, help me figure out what's wrong, thanks.