f150 power loss need help
 

I have a 2005 F150 4x4 5.4 liter with 130000 miles. in Oct last year, I noticed a power loss hole trying to pass. when trying to accelerate from a stop or trying to pass the engine shifts normally but has no power until the RPMs build up to 3700 then it accelerates normally. When accerating fast from a stop it feels like it is going to fall on its knees initially. it idles fine. I have had new plugs, phasers, fuel filter, timing chains, and computer put in vehicle without improvement. Told cats are good, throttle body good, intake fine. Have been told fuel pressures are fine. It has the classic tick that all these trucks seem to have (told it is a lash adjuster). I do not hear a knock when accelerating. Ford says spark not advancing due to knock sensor. NO CODES. Ford now says need new engine. Say disconnecting knock sensor eliminates issue. I did not find that when I disconnected.

Any suggestions?