I have a mitsubishi galant 2005 and just resently it's been smoking (white in color) alittle from the tailpipe and has a odd odor. The odor isn't consistant either. It doesnt smell like hot rubber and the car isnt running hot. It also still has smoke coming out of tailpipe even after the car is off! It doesn't last long but I dont think thats normal at all. What's the cause of this?