I have a 92 celica, and if I drive for awhile, the car will start bucking, and eventually stall whenever I come to a stop. If I drive without my gas cap on, it runs perfectly fine. I had a venting problem a few months ago, and replaced the gas cap(it is a venting cap) and it solved the problem, but not it's happening again, I don't think the cap is the problem since it's new. Where else does the tank vent that I could check? and how can I clean it?