08 t660 loss of power at higher rpm. intermitent.

2008 t660. When I hit higher rpms, sometimes the truck just looses power and I have to drop speed/gears to get it to want to power back up. its not a clutch slipping problem. I just replaced the clutch. it was slipping before this issue and this issue has been going on since the clutch has ben slipping. my speedo just started jumping up and down. sometimes working and sometimes not. wondering if you think it might be speed sensor?

 

Hellllppppp meeee please... lol

 

Isx 485 HP 13 speed Eaton.
It doesn't only happen when speedo is acting up. Sometimes I get a white smoke trail.