Conversation Between 70f100longbed and MAHighboy77

I know the FPDM's go bad in these trucks, also injectors clog, as well as over time they have back fuel pressure sensors in them. But none of these common problems convince me the problem leads to them due to the truck running great when I run seafoam in the gas tank.

I have a 2006 with the 5.4 and I have done the same all 8 plugs, 8 cop's, i have changed a few injectors yet I still get misfires. Now when I run injector cleaner or Sea foam in my truck it runs fantastic for about 500 miles, about a full tank and a half then my problem comes back. When i changed the plugs about 2000 miles ago I found a few broken plugs, can assume that this caused my passenger side Cat to go bad? Causing a very slight break down at idle, then on the highway under slight load i get a check engine light flash throwing misfire codes, but if I keep her under 60mph in OD she runs fine with still a very slight break down causing the engine to shimmy but no buck. I hooked up to my car trailer this weekend, when i got on the highway and got it up to 65 I instantly got misfires. It seems you are a well educated 5.4 guy, could you please provide further info that would be great!