Ok I'm going to try this one again and see if I get any "more useful" feedback.

I thought my tranny was shifting fine up until a few Months ago it shifted into what seems to be ANOTHER gear.
Normally it shifts into final gear(at freeway speed) and upon Acceleration the RPM's advance, the Turbo Spools and the MPH advances. BUT, every once in a while I will accelerate up to speed and after reaching(what I think) is final gear, it drops down again into a very low RPM (like 1500@ 60MPH) and upon acceleration the RPM's do not increase like before. What happens is the RPM's slowly come up WITH THE TURBO and a massive amount of power and acceleration occurs, like enough to make it hard to hold your head up! Also sounds much deeper and nastier when accelerating. Talked to my Mech. and he basically blew me off. ANY CLUES?

 

Sounds like the TC locking.

 

That is the TC locking up. Its supposed to do that. I would be worried if it doesn't do that.

 

Yeah well it just did "it" tonight on the way to work ONCE, but I slowed getting off the freeway and it didn't do it again ): I'll have to give my mech a shout again and see if I can convince him there is something wrong! Amazing that it hasn't worked right the entire time I've had the truck and now after 60,000 miles it starts kicking in!!!

 

check your lockout/towhaul switch.
Clark

 

ditto! If you are in tow/haul mode it wont go in. im sure you know, but its the button on the end of the shifter....OD on/off.