It shifts late ,2 gear at 2500 3 & 4 at 3500 after releasing gas pedal only

The transmission *detent cable* needs to be adjusted! .. Also called - passing gear cable - throttle valve cable .. That's what controls transmission shift pressures and rpm shift points .. This cable is located on the throttle body linkage along with the actual throttle cable .. The more that 'cable' is pulled outward by the throttle linkage - the higher the engine rpm must go before transmission will shift .. To make the transmission shift sooner - adjust more slack in the inner 'cable' by adjusting the *cable housing* toward the throttle linking so it doesn't pull the inner 'cable' out as far .. Adjust in small increments until desired shift rpm + throttle pedal position is achieved.