Lately like in the last 3000 miles or so my truck doesnt want to downshift an go.. especially when I want to pass or get on the freeway. Feels like a civic with 5 fat guys in it.. Gas milage is good the trans shifts good.. An I have noticed an ever increasing stumble when it is cold. I have 110K.. Any ideas.. raining here so I have the day off want to get this figured out. An it cruises good you would never know there was a problem until you want to punch it an go.. I checked the normal stuff.. Plenum, plugs, cap, rotor.. all seem to be fine an the tune up was done about 11k ago cause the plenum was bad. An the cat seems solid.. no abnormall clanks.

 

sounds sadly similar to the situation I had when I first got my truck, I have a 99 just rolled 90K. when I got it about 2 years ago with around 52K I had a few problems with it and the stealership told me I had a misplaced rod and the tranny needed to be rebuilt. surprisingly I didnt have any codes misfires or anything like that, my only symptoms were the fact that the truck really bogged down when I gassed it, and a slight fluttering sound when the gear was gettin to the top of its band about to shift. I actually took the truck to the stealership to have them check the noise and they came back with the bad news. I hope for your sake its not that serious, but a place to start anyway. Luckily mine was under warrenty so I basicly got a new trans and engine for the 200$ in deductibles