2006 F-150 5.4 Triton, backfires and has no power.

Ok I really hate to be bearer of bad news but these 5.4 had tons of major issues infact ford got sued over these motors for all the defected parts in them. Let's start off with a few things backfire could be distributor. But let's address their major problems with their spark plugs first their spark plugs only went in 2 to 3 threads so they were just blowing right out then they went with longer spark plugs , actually to long but the main problem was they were putting a steel spark plugs a into an aluminum block and it was a two piece spark plugs and they would break very easy and they would get oxidized into the motor and you couldn't get them out, so they started putting anti seize on them the only problem with that was to much antiseize totally threw off the electric current that operates the spark plugs . The other thing is the roller rockers they put in them were a great idea but they were cheap and they would crack resulting in a ticking noise then eventually catastrophic engine failure . Next thing, all these manifolds would bust as early as 20k miles they had tiny studs that we're to small holding the manifold on and once again it was a steel stud going into alunimum and they were absolutely a huge pain to change and a busted manifold can cause huge problems now you have to drill out the steel stud then your drilling into the alunimum, not good . Back to the spark plugs the only way ford so so fixed the plug issue was by helio coiling every spark plug port. My suggestion is get it into a mechanic asap but your probably looking at an expensive rebuild or replacing the entire motor and no more of revving the engine you could grenade it like right now if it isn't already grenaded. If you go with another motor see about putting a 5.0 in it 10000 times the motor. I'm really sorry your dealing with this whoever sold it to you knew about all this that's why they sold it good luck.

Now on a better case scenario it could be a sensor like cam sensor, which would explain the fuel issue some what or tps,( throttle positioning sensor ). Now if you get lucky and that fixes it , which we all hope it does , slap a for sale sign on that truck and get rid of it just as fast as you can!!! Or trade it in the point is unload it !

Have the catalytic converters checked for excessive back pressure.

Check the O2 sensors -- that is the one of the main causes for the too rich / too lean issues. Be sure to rule out vacuum leaks. I have a 2006 4.6L with 190,000+ miles -- They are reliable trucks, but you need to take care of them like any other vehicle.

06 5.4 have no distributor backfiring is usually caused cam timing in these engines the only way to find out is to pull front engine cover off most modern engine's are made this way