The car has been really good till recently the cat clogged and killed the EGR valve and the O2 sensor was not running to spec so replaced that as well. The car now thinks it is running rich so it leans it out and now when you go to give it the gas she lurches and stalls. Restarts instantly and then goes. Really stumped on this one pulled the throttle body and cleaned it completely and replaced all the gaskets the throttle position sensor is right on spec. Other then the stall it runs great. Anyone got a clue on what to even look at? Thank you Car has just 65000 original miles on it 3.1 liter

 

If you would,
How did you determine it is running rich? With the right scan tool the fuel trim can be verified as well as the O2 operation

If it was running rich and cooked the converter, are you sure you corrected the real problem? Did you try to disconnect the EGR valve and control to eliminate that as a possibility?

 

Hi Hanky,

We did replace the EGR valve as part of resolving the clogged Cat. the O2 sensor was way out of spec on a meter so that was replaced the scan tool still shows a lean condition and she seems to be dumping fuel. The issue is only when you come to a start or first start it up and try to go she bucks a bit like an old Carb that has a bad float or needle valve sticking than either stall 90% or jerks then goes. The fuel pressure check is on the money she holds even after the key is off nothing seems to be leaking. Other things that have been done are Fuel filter was changed 3 months ago because of age gas was drained from the tank and refilled. All sensors on the throttle body are brand new AC Delco and all appear on the meter to be in spec Throttle body was ultrasonic cleaned and all new gaskets. New fuel regulator was installed last August. Much of the work has been done to resolve the high idle issue the car had last summer all was running extremely well up until 3 weeks ago when the stalls happened then a power loss we put to the Cat clogged. 65000 originial miles on the 3.1 V6. Also no codes or check engine light last time we had a light was months ago and the code was 12. I am kind of leaning to a bad injector as the issue they are the original. Any thoughts much appreciated.