Today I also checked the compression with a better quality tester. I am able to get 190 lbs on all six cylinders. The only weird thing is, on the #3 cylinder (the problem one that I get a p0303 code) I get a different sound from the others. When I test the other cylinders I get a rythmic sound and a feel when there is compression. When I do #3 within a 15 cycle crank I get about two or three that just doesn't sound or feel like the others. Sort of weak sounding. Could I be getting a lack of compression on just two or three compression strokes? Bent valve? Sticking valve? Maybe bad valve spring?

 

prob valve spring issue