Recently I noticed that when I need to pass or quicky merge in trafic with wide open throtle and it does not matter if it is from rest or already moving..it usually get stuck on 2 or 3rd gear and unless I let got the pedal it will not shift to next gear...look it is trying since the RPM drops from 3200 to around 2800 and if I keep holding it sometimes switches...but not often..when I drive half throtle it works as before....any idea if that is a trany problem or something major...thanks for you input....the truck has 96k km...