Upon starting, my car will hesitate as though it's about to stall. The engine runs very rough and rich. Sometimes it will stall. The Rpms drop and bounce around. Also, the lights will dim as it feels like its about to stall. However, if I get the car running for a bit, it will go away when I can get it up to speed. After this, I can let it idle for a while, or keep driving, and it runs completely normal. The other weird part about it is that this only seems to happen when I go shopping or similar scenarios where I turn my car off for only a short period of time after having driven it. For me to wake up and go to work and likewise to come home, it never acts up. I've taken it to two places, both of which told me they don't have a clue. It just sucks that I have to spend at least five minutes trying to drive before I can do anything. Also, a friend was looking at my car recently and we noticed a single ping that happens regularly about once a minute or so that's coming from the engine. I don't know if that has any relevance.