Drove truck 150 miles yesterday and bout 4 miles from home I felt a stumble for a 5 seconds, then it went away then came back, went away and now it stays.

Pulled codes and it says p0300, random cylinder misfire. So I started pulling plug wires and no change came from 1,2, and 4.

Havent changed nothing in a couple years other than the walbro 255 had unclipped itself from the fuel pump harness bout three weeks ago.

Thanks in advance for all help.