Okay i noticed the other day while i was idleing some white smoke was coming out of the muffler not much but enough to see. When i press the gas it goes away but as soon as you let off of it reappears. Whats going on here. When the car is cold there not much sputter when it warm once and a while if feels like its going to shut off but it doesnt. Also now when i floor it it will hesitate like its gonna die but then pick back up. Any help?