2008 Silverado 5.3L 4 speeds,, now it has a 6.2L engine. it runs pretty good, shift ok under normal conditions but at WOT it will pass the 6000 RPMS and it would not shift to 2nd gear, i need to release the accelerator to allow the trans to shift to 2nd gear.. those are the current tunes on the truck..
what do i need to look into?