1999 jetta 2.0L misfire problem
 

I have replaced the plug wires on this car, and it is still missing, diagnostic code P0303 (#3 cyl misfire). Happens more when warm, and after putting a couple bottles of fuel injector cleaner and good gas in it, runs much better. I bought a new fuel injector to put in, but not sure which one out of the 4 to replace. Does anyone know which one corresponds to the #3 cyl?

Thanks for your advice.

-Wilma