96 Taurus hesitates no power
For the past year my 96 3.0 liter Taurus has a symptom that occurs only after running at high speed (70+) or very HOT days (Houston).
As long as I have a constant high speed, the car runs and accelerates fine. Then when I slow down or stop the car hesitates with little or no power when I try an accelerate. Most times if I turn off the ignition (from neutral) and then restart the car this will clear the problem. Recently the turning the ignition off then on does not clear the problem.
On rare occasions, the check engine light will flash and the car will shut down.
I have replaced the Mass Air Flow sensor.
Some of the codes I have recorded from the computer memory include:
P0171 System too Lean (Bank 1)
P1131 (Lack of HO2S11Switches - Sensor indicates lean).
P1131 (bank 1)& P1151 (bank 2) fuel/air ratio is correcting rich for an overly LEAN condition.
I assume that if I had a vacuum leak this system would exist all the time.
I am at a loss.