Jay, The air flow sensor piviots the control plunger up and down in the fuel distributor with back pressure coming from the control pressure regulator. If the control plunger in the fuel distributor is adjusted to lean and your on the border line of the plunger sitting to far down as to not allow fuel to the injectors, then what your describing will happen. Just a 1/4 turn, I think clock would make a difference in the air flow plate which adjust the control plunger. It's like tinkering with a clock. As the 02 sensor ages and changes the voltage that goes thru the ECU to adjust the Frequency valve which changes mixture of air/gas this is why over a period of time the cars have to go in for as check up and adjustments. The only other thing would be the back pressure of gas going back to the tank. But, if you have a new fuel pump, is not likley the check valve would be bad.. Also, make sure the wires on the CPR or warm up regulator are good. In the warm position, the CPR should have very little effect on the plunger. John Hervey www.specialTauto.com