i had a master technician look at it from my das job and we couldnt really find the problem there was a weird error code. and what happens is that when i turn it on when the engine is cold its fine but lets say for instance i go to the store turn off car come back like 10 minutes later and turn it on it idles real weird like it will shoot up to like 1000rpm than just drop down to like 250. we put a new alternator in i checked the spark plugs there intact. like even sometimes if after i get in after the engine has warmed up and im coasting through the parking lot and have to slow down to stop or like under 5 mph it will stall out like the battery light will come on and the steering locks up simillar to when i one time ran out of gas (haha) well anyways if anyone has any suggestion sto what might be the problem or can tell me how to fix it it would be greatly appreciated cause im thinking of selling it and i don twant to until i can fix this prooblem oh and this started to happen like a month after i had flowmaster 40's put on cat back dont know if this is coincidenc or not? and it also happened first time i put premium in ther ealso dont know if thats a coincedence??? thanks to all who help =)