Ok well i changed the CPS, (camshaft position sensor) and the idle smoothed out. Changed the oil and the antifreeze. Had a thermostat problem and fixed that. Took it out on a highway test run and still lacks power. CEL flashed on me and continued to flash. Not a steady state. I got home and pulled a P0304 code. I now have two choices that I see. Replace the fuel injector in cylinder 4 which I am going to do and see if that works. My other choice is the cat. Can anyone HELP me on this? Am I even getting close?