[DVSNCYNIKL]

It can be a number of things. You just have to narrow it down through the process of elimination. You might need a tune up. You might just need to clean the injectors. Could be the plugs. Could be the timing. Could be water in the fuel lines from condesation. You have to do little things to see if it stops. If not, it could also be your timing needs adjusting. As you can see, many possibilities. If you're doing it yourself, then you have to do these things or you could just take it to a mechanic and he'll find out for you.