please help

My service engine lights stays on, it gives the code p303, cylinder 3 missfire, i was told to change the coils so i did and also my spark plugs and the light is still on, what else would cause a cylinder 3 missfire,

What kind of engine do you have, year?

If your engine is a Quad type then more than likely the problem is a failed Ignition Coil Housing where the ignition coil and ignition coil module is located.

p0303 is most likly an Injector.

The only way to clear the code is with a scannnig tool.

try some injector clear. and clearing the code.

If it is running rough continuously , and performance is poor, you'll probly need to get it to a shop and hav it looked at.