Hi Dan and Karl! So here's my question to clarify things--do you use the throttle angle that is read on the scanner with the engine off but key on? This 06 avalanche (3 bolts not 4) showed 19.2 I think with the key on engine off. It read 8 or so w/ engine idling hot. I scribed the bore at both these numbers w/ scanner plugged in key on. Then I went astray thinking I could hold throttle closed shut and use 30 degree angle on large bit. I touched top of bit to butterfly and tried to hold a 30 deg. angle,this would "kick" the Groove inboard from the butterfly at closed position. It did but not nearly enough! I also didnt use a vice, so it was awkward. The Groove worked, but too "early" in RPM and vehicle speed. BIG surge of power immediate off idle, anything under 25 MPH required brakes! Then power sagged. How do you guys position the throttle blade in the right spot to cut the Groove? Getting an angle measurement w/ scan tool and marking the bore is easy enough-- but past that im all wet here. I must add that doing the computer re-learn was Interesting. At first RPM would fly to 2500 at start up then pull back some. After 15 starts in driveway then about ten re-starts on the street still only up to 25 MPH it started to pull back the RPM's. Eventually it was starting going to 1850 then pulling back to 5-6 hundred fast. Did probably 40-50 restarts up to freeway speed at end. Next AM cold start it immediately went to 1600 then settled to 650, acting docile. But as soon as truck was backed out and throttle opened at all it was off to the races!!! Wow.... "Groove works but can be stern teacher!" Thanks guys, TracyG!!