I'm new here, and have the same sort of trouble as you Calvin.
I have a 2002 f-150 4 x 4, 4.6L Romeo engine. All the plugs have been changed, the injectors checked out, and I have no OBDII codes that show up, still I get an erratic missfire. It gets worse when it is warmed up. The fuel presure is 30 to 35lbs when driving down the road and no blips show up on the guages during missfires. I have a scanner that tells me of missfires as I'm driving, the missfires are random on the cylinders, never the same cyl. Compression and leak down have been tested on all cylinders, and all is even. I got a tip from a Ford mechanic that it could be the EGR regulator, so I replaced it and the results are the same, erratic missfire. Anybody else have the same problem and fixed it ?
Thanks for any help I get.