eng surge then stall
 

93 buick roadmaster estate wagon 5.7 . this started after fuel pump went bad. after start eng idles at 750, as eng warms idle will drop to 725 then raise to 800 down to 700 getting progressively worse to the point of stalling. some times it kicks the check eng lite on and the car runs fine, shows code 45, run rich. have since changed the fuel pump and filter again, cleaned idle solenoid and passage, reseated connects at computer, tried to clean 02 sensor, shroud prevents cleaning tip!, changed tps, cleaned vacuum ports at throttle body, reseat connects at coil pack. haven't cleaned egr yet, but its showing no codes . any ideas out there?


thanks craig

Pull the vac hose off the FPR and smell for gas.

this is tbi car I don't see a vacuum line, the fpr is on the tbi? got looking at the evap canister,the hoses on the control valve on the vent line are crumbling , could the tank vent being blocked cause this problem?

thanks Craig