My Shadow just gulps fuel like it's nothing. It uses more fuel than the T/A. I tried some STP fuel system cleaner and that seemed to help a bit, 2 tanks later and I'm back to the ame ol' crap. There seems to be black smoke at times, and the engine has a somewhat smooth idle but will jump at times. I'm just not that great with cars so does anyone have a general suggestion. I've tried to do some research and I will probably replace the O2 sensor(I think it has just one). Another place said to check the plugs, wires, and distributor. I just dont' know what to do, HELP