Cliffs: Car idles at 4k after boosting to redline. No idea why. Read for details. I have an '05 Evo GSR. I bought it with a few simple mods, figured I'd add to it a little and leave it at that. Came with AMS turboback, K&N filter, Forge DV and MBC, Walbro pump and AMS tune. Things were great, wanted a little more power, bought some cams and a lower IC pipe. Cams and LICP went in no problem. I had to wait about a week and a half between doing the cams and getting the car tuned. It's my daily driver so I took it very easy. I only got on it twice....once to make sure everything was good right after the cams, and once a few days later. Other than that, just normal putzing around. So it's getting tuned, and on the baseline pull it boost and gets to redline fine, tuner lets off the gas and it drops to 4K RPM and just holds....and holds, and holds. It sat there for a good 10 - 15 seconds. Long story not as long, it keeps doing that. I've tested almost everything I can. Here are the facts: 1. Doesn't do it at idle like in a parking lot, seems like there has to be some bit of load on the car 2. The throttle cable moves fine and does not bind up anywhere. The throttle body does not stick open. I've had a scanner hooked to the car and the TPS reads the voltage correctly and does not drop out anywhere. The IAC is not the issue...I switched mine with someone elses who I knew was working and the problem stayed there. There are no vac. leaks. 3. I disconnected the harness from the IAC and the problem went away..? I drove like that for a while (I'm waiting to get back with the tuner) but had some problems at idle when it got cooler out one night. When it's warm it's fine with it unplugged, but when it gets cold it idles for shit and will stall on me. I have no idea what it is. Because it happened while being tuned, the tuner looked at various things and nothing seemed to help. Told me to replace the IAC and if it didn't fix it to let him know. It's been 8 days since I was tuned now and I haven't heard from him yet...I've contacted him repeatedly. I can't think of anything else it could be other than something in the ECU telling it to stay there under whatever conditions. I don't know how it got there, but I can't really find an explanation for any of this. It's the only thing I can think of as to why it would work with the IAC disconnected but not with it plugged in. Any input?