Details: Not in an f-body but cant find any help on any other boards.


The trucks a 2003 sierra extended cab with a 5.3 liter and 88,000kms. The truck seems to run great but having a little trouble with power at highway speeds. Driving highway speed and when flooring the truck it seems to only gear down one gear and only be reving at 2200 -2500 rpm which makes the truck seem slow. I'm not sure if this is a transmission issue or a engine performance issue. First thoughts were the pedel travel seemed to be rather short compared to my 2004 silverado with a 5.3 and that the pedal wasnt giving the engine full throttle. But at an idle the truck will rev to redline so im thinking its not the case.
If anyone has any ideas where to start looking it would be greatly appreciated. Because i no my old 04 would drop two gears and be be reving at 4000rpm + when flooring on the highway to pass someone.