I have a 1990 camaro rs, V6 3.1L, automatic. My car starts up fine, runs good, sounds good, but when im at a stop light or coming to a stop my car will stall. i throw it into park, turn the key and car starts up right away. This happens at random times, doesnt matter how long i drive, and when im stopped the car will start to idle rough and sometimes it will stall, other times it wont. It does not idle rough every time i am stopped. The car has recently had the spark plugs, wires and cap changed. Also a recent oil change. The vacuum lines are fine, fuel lines are good. When i take off gas cap it sounds like pressure is being released. Any ideas on whats wrong?

 

My car makes the hissing noise when I remove the gas cap also, but haven't had stalling problems. Are you sure the plugs were gapped correctly? Did it do this b4 you installed the new plugs? My sister had a '89 Grand Am a while back and it had that problem b4 and after we changed the plugs, coil and spark plug wires which were actually like plastic cups that fit over the plugs. After throwing parts on it and scratching our heads alot we put on a cheap set of AC Delco plugs and it ran awesome after that. Not saying you need new plugs for sure, just relaying a past experience.

 

the car never stalled or idled rough before or after we installed plugs, which was about 3 months ago. It just recently started randomly stalling and idling bad. And the only thing i have done to it recently was a new paint job and new rims put on, which has nothing to do with it

 

Try checking the fuel pressure regulator, my truck had the exact thing you are describing and the diaphragm was torn. If you can get to it, pull the vacuum line off and have someone turn the key on - if fuel comes out, replace it. Its a pain to get to on the 3.1, you have to take the upper intake off (I did this on my old 91 when it started running rough the week after I sold it).

 

i took my car to a mechanic and found out that the o2 sensor was bad, throttle body was dirty and i have three bad fuel injectors. since i dont have money right now to fix injectors i just had o2 sensor replaced and throttle body cleaned. so i drive my car with the bad injectors, but i only drive to school and back cause i know this is will lead to other problems, and because i use a lot more gas. the car still stalls, so the injectors were the main problem.