I had this setup for a while now. Have an oil leak problem from the exaust but the car ws running fine. Today the weather got a lil colder and the car started turning off every time i stop at a signal light. Also noticed that it idles very rich for 20 secs and then it goes normal but the rpms goes " low-normal, low - normal" constatnly. I also found grey/silver powder kind of stuff on the exaust tip and all over my rear bumper. First i thought it may be because i have low oil so i topedup and tried but no luck Any ideas? Could it be my MAF? Any help appreciated.