I have searched the threads and can't find a similar problem. My 2000 has the 4.6 engine, had it since new, regularly serviced. Superchips programmer, K&N, Flowmaster. I have been hearing a rattling or ticking sound from the top end at WOT just at the shift point. Normal shifs take place just at or above 4500 RPM, but from time to time it seems to wait a bit longer and shifts closer to 5000 RPM. It is at these higher shifts that the rattling appears. Years ago I had a big block Olds 442 that would float the valves at higher RPM's and new double coil valve springs cured the problem.
So, is the top end starving for oil at higher RPM's or is there valve spring problems, or something else? Also, why the difference in shift points at times?

 

Pinging maybe? Run some seafoam thru it

 

Not pinging. I put 92 or better octane in it all the time due to the Superchips program. Once in a while I can only get 91 when on the road and get stuck with what is available. It will ping with it when lugging up a hill, for example.