Code P0304?

When changing rotor, I noticed play in the shaft though the rotor was tight. Is this normal? The problem started with a flashing SES, codes p0304, p0420, p0430, used cataclean, light went off, passed smog, light came back on code p0304. Started have security issues- wouldn't start, changed fuel pump thinking that was the problem. Changed connector to map and temp sensors. Codes were p0174, p0304, p0420, p0430. Changed plugs, wires, cap, rotor, and oil. Code now down to p0304. Trying to figure this out. Truck starts every time, check engine light is always on, that's the only two things that are consistent. It seems like it doesn't start flashing until I have to decelerate and then reaccelerate without dropping a gear. Stops flashing when I go below 1000rpms, lots of the time you can't feel it missing when its flashing. I tapped into the gas line just after the filter and sprayed cleaner thru the injectors then I changed the filter and the 02 sensor, still p0304.