Ok here it is when ever I do a wot pull on the street from 1st and let off as it shifts gear and i get a belt sleep nose like the supercharger wanting to go ether faster or slower than the crank .now remember this happens after i let off the throttle .This truck has a idearler bracket and right size belt .So is this the bypass not leting pressure off. thank 2002 lightning

 

that's just belt slippage... nothing to worry about.

 

Belt sleep nose you say? Nope, never had that problem before! Sounds like a bad one though!

 

I have heard of slipage under load but not like this could it be the the vacume actuator out back is out of adjustment there alot of play in them

 

When you hammer then let off, do you hear it slip when the tranny shifts? mine wiil do this becaue the accessory drive belt is the one slipping making that noise. It's common... Nothing to work about....

 

Like previously stated, it's just belt slippage. Mine does it too when I go WOT and let out just as it shifts to 3rd. I think your starting to over complicate what's happening.