im having the same problem also wondering if a clogged cat would cause back up to causing everything to compensate for the vct and cam sensor codes?? i had both replaced already it all started with a misfire in cylinder 6 but ran it with the misfire for a while then truck just went hay wire n would barely run and got a bunch of codes replaced all the coils n plugs cam sensor vct both sides cam sensors on both sides n that was all from ford n still have a problem with the p0340 code coming back only if i drive the vehicle for like 3 miles.... n then runs rough barely runs.. shut it off for a day start it up n runs fine for like 3 miles.... so if u figure out whats wrong let me know ill try it also... 4.6 mountaineer