Engine knock and rough idle problems

[chredman]

Hi I recently purchase a 2000 7.3 and it is making a knocking sound on the driver side of the engine, and it idles rough. I first check the injector harness on both sides and they were fine. So next I bought a fuel pressure gauge and my fuel pressure is 53psi. I thought I would try to bump it up a little so I put in a stiffer fuel pressure regulator spring and still 53psi. Next I changed the fuel filter and the fuel bowl was really dirty so I cleaned it all out and put that back together still the problem. After that I changed the icp sensor and took back off my valve covers and check the injectors they all seem to be oiling the same. The knocking sound is the loudest from idle to 1600 rpm after that it isn't as loud, and if I am driving down the highway and let off the gas the noise goes completely away for a second. I can tell that the truck is down on power.