97 cavalier 2.2 stalling.. need a techs help.

i have a cavalier that stalls at 1/4 throttle every time. especially when cold. i hooked up my gm advanced scantool and i have no codes. i checked tps, iat, ect, inj pulse width, baro, intake vacuum, egr and it all looks good. the only thing i didnt like was that the evap purge solenoid was activated most of the time i was driving. on one fuel throttle accel test i had a rotten eggs smell from exhaust. my fuel tank pressure was mostly at a negative number suggesting it had vacuum all the time. my long term fuel trim (-11) is lean so the ecm is compensating for a rich condition. i am getting a 14.6:1 air fule ratio. possible evap purge solenoid sticking open?
thanks for any suggestions.

something tells me you know more about your problem than anybody here.

but i truly hope somebody knows the answer

:lol: I'm with him. www.jbo.org (http://www.jbo.org) probably would be your best bet. I can try to help though. I would say clogged cat. I have heard that a clogged cat will make that rotten eggs smell. When you are idling, the air is able to make its way through the clogged cat but when you are trying to put more air through it that it can handle, it just pressurizes and chokes off the engine from behind. I think its worth a shot, check that evap solenoid too, that sounds like it could be too. Also, 14.6:1 AFR's are wayyyy the fuck too lean, I wouldnt run that shit until you can figure it out.

found the problem. the right wheel speed sensor had a bad connection at the abs/traction control unit so the traction control kept kicking in thinking the wheels were slipping. the traction control system takes away fuel when this happens causing the engine to stumble. i also had bad missfires from a leaking valve cover gasket cuasing some of the stumble. the oil was leaking into the spark plug holes.