Code P0300

Okay so, I replaced the fuel pump and filter recently because it would not start and stay running it sounded like it was running out of gas. The pump intermittently would kick on but no pressure at the fuel rail. Now my truck is having trouble during start up and idles really rough after it gets running. I have to hold the key in start position for way longer than I should. The roughness smooths out at higher rpm but while I am at freeway speeds the rpm's fluctuate. It will jump roughly 1,000 rpm's. I have already replaced the injection system with the updated parts also has a new coil pack and distributor, plugs and wires I did last year as well. I am thinking maybe EGR or something along those lines will be next.