Alright guys My truck has 67,000 miles on it. It's a 90 model 3/4 ton Suburban. 400 tranny. About 1,000 miles ago it started shifting back down after it had shifted up. Just for a second. It would shift up like normal and just fro a second kick back down and then back into the right gear. Like it needed just a little more oomph to get the right gear. Well now... It's not wanting to shift up nearly as easy as it used to. It sounds like there is a huge fan under the truck spinning like mad. This truck has been maintained like no other. I've never driven it hard, but I got the truck with 60k on it. What could this be? My guess is that the torque converter is about to go. Damnit!!!!!! Just when I almost had enough to buy my tires and wheels. How much is a TC gonna cost me? If that's the problem.