I had the code 32 coming up so I changed the EGR valve and men the ran so smooth between the gears and during slow acceleration like never before. Then coulpe of days later it ran little bit rough, then I got the injectors flushed because my car has had time starting some times. The car ran smooth again the next day its back to rough. I didn't do nothing any more and now some day the car runs little bit rough and some day it runs like a dream, what would cause this to happen? I am thinking of opti or fuel pump