The two Comanches I had before this one also had a high-idle problem. The high idle problem was caused by vacuum leaks and tightening the exhaust manifold bolts took care of it in the past, but on this one, not so much. After swapping in a few used and then new TPS and IAC sensors, the idle went back down, but halfway back home it was up again. I found cracks in the header that I couldn't weld without removal and I hate doing headers in these things. Instead of doing all that work for no gain, I ordered this APN header for $139. It comes with a gasket and bolts for the head pipe. I had great results with the sealing of the 505 Performance gasket on the Insane Inline II and had ordered it (bottom) when I thought I was going to get away with just a gasket.