When I removed the intake, I noted all the small ports were all clogged with carbon. Both egr valves were also carbon contanimated too; allthe way up to were it bolts to the bottom of the intake. The flimsy metal hose that is around the back Brett, is also part of the emissions recirc sysem...I think; removed them while doing the work; they were also clogged. One thing you can ck, is the air-port plug right next to the oil fill cap. Remove it and see if you can pass a stiff wire. They are probably clogged as were mine. All these tie into the emission/adaptation curves and how the computer compensates. The long runner design will have secondary back pressure gases and will cause carbon build-up. This was a documented problem with GM's TPI engine as on one of my older Vettes. Removing these and servicing/cleaning are a test in your abilty..believe me. Now I know why someone removed the cel before I bought the car. Good luck PS don't forget to ck the wire harnesses!!