Said I'd post back with mileage results, and here I am! First, serious difficulty getting data from a car with multiple drivers.

Initial tests were questionable, but eventually I did get a couple of tanks where mileage was "up" to around 17. Still very disappointing, but a big improvement over 13.

I did another once over on the various vacuum elbows and hoses. Changed several things. The next trip was one I made in the car, almost strictly highway. Mileage came in at 23+. Good, but still not where I think it should be, and compared to the 17 for city, comparable.

Next two tanks were down around 17-ish again. Just from general use, we still feel we are using more than we were six months ago, and if the readings are any indication, that's probably right.

This car is running a replaced AMM. Our original failed a couple of years ago. New, clean air filter. Plugs, wires, cap and rotor all changed less than 30k ago. New front o2 sensor. ECU was chipped by SpeedTuning over two years ago. Skip 'n dip fault has never been fixed, but rarely shows up, and the car runs and drives very well--just this niggling mileage thing. I'm thinking of sending the ECU to Rob Arnold to see if he has any suggestions. Maybe something is wrong there.

Any tips will be appreciated. No codes showing. I'm going to do an air test on the evap system and see if I can locate any leaks.

DS