Strange....I pulled the head off 3 times in my quest to change my first headgasket and the first time I put it back on, I put the gasket on upside down, so I was leaking coolant from the IM because of the gasket, when I started the car, 3 quarts of oil leaked from the head, and I had the erratic idle. There must be an air leak somewhere in the IM. Look everywhere and see if you can find it. Also, make sure that you tighten the IM bolts in a crisscross pattern or else it won't seal right. I just took the bracket holding the IM up off and threw the damn thing as far as I could. It makes tightening everything much easier.

I really don't know what to tell you...just search for the leak near the IM gasket because that is where it most likely is.