If you're tuning with the sensor you will notice a few things. The Avenger has a better system of internal passages. IMO the cruise at 15+ is fine. The 750 is oldschool and just flat out doesnt. What you want to be concerned with is the fuel curve. Get a vacuum gage and hook it up with enough hose that you can drive the car with it taped to the window. Watch the gage and where the needle hangs at various throttle openings. You can adjust you power valve rating to get the valve to open exactly when you need it. Most guys just get one that stays closed at idle. That's important too, but by tuning the PV properly you can get great drivability. My guess is the 750 is rich because of that and the 670 stays closed for a longer period. If it's a hydraulic cam, you can go as much as 2/3 turn past zero lash if you have to. It may pick up some idle vacuum when you do this too.
