Ok, I have an '06 5.4l f-150 with right at 70k miles on it. probably 5-7500 miles ago i had both catalytic converters changed under warranty because they were plugged. truck ran fine for a but i could then notice that the cats were popping (sill are today every now and then). Well when i accelerate to get on the interstate my truck loses all power at 3200rpm and just stumbles. I normally get a p0307 code (cylinder 7 misfire) well i was told to check a ton of things and ended up changing the coil no injector to no success. what would y'all say the problem could be? I'm thinking its time to go ahead and change the plugs before i get to to high of milage. and was thinking that it ould be fouled plugs since the cats. were bad. I was thinking that the plugged cats could have fouled them out...

I just on't understand i work on diesels all the time at work, but this thing has me stumped.

 

i'd start with plugs and wires. they may or may not be the problem, but the truck is about due.

 

No wires, his truck is COP. May want to replace the #7 COP. (EDIT: nevermind, just reread and saw you did)

Service Manual lists the following as possible causes of the P030X Codes

Ignition System
Fuel Injectors
Running out of fuel
EVAP canister purge valve (I've heard of the vacuum line cracking on these)
Fuel pressure
Evap emission system
EGR system
Base Engine (hope not)

Hope this helps.

 

There are no wires on these trucks.

Could be a plug but some others might have some suggestions also.