My car is stalling out at lights or when I go around corners. I had a check ran. on 1999 Buick Century

it is popping and sputtering at times backfires and smells like rotten eggs. I had a mechanic look and could not find a thing.

Asked by for the 1999 Buick Century
first check the tune up for back fire.
rotten eggs smell - is it coming from inside the car or outside. if it's inside the car check cabin filter. more question feel free to contact us at 951-737-9411