Help!!!! No Acceleration, Doesn't Shift

[yellow submarine]

Help!
Wierd Problems with acceleration and shifting.
4.0L automatic 2002 sport trac.
Vehicle does not seem to perform over about 3-4,000 rpm.
Engine does not seem to run out of power and will spin all the way up to 5,000-5,500 rpm.
Under Heavy acceleration the transmission will downshift but once it passes about 4,000rpm there is absolutly no acceleration, it will get up to about 50-55mph and just sit there, engine will rev out in that 5,000-5,550 range and the transmission will not upshift until I take my foot off the throttle, then a couple of harsh upshifts and it will then accelerate.
I can only get about 70-75mph out of it, and thats only if it stays in overdrive slowly accelerating without initating a downshift. If it downshifts even one gear it won't accelerate.
from about 75-80mph, 80 can be hit downhill, haha, a light humming/vibration starts.
Also the tourque converter doesn't seem to lock up when its in overdrive.
Anyone had this problem? The truck has been to many dealers and nobody has diagnosed this problem, seems transmission, maybe tourque converter issue to me. Engine feels like it has power, but just isn't transfering it to the ground.

 

[bdmaash]

looked at this post a while ago, no replies yet

- catalytic convertors almost plugged
- transmission problem

you'll eventually have to admit defeat and take it in for service. Usually the sooner the problem is looked at the less damage is done to the system.

 

[mbautodesign]

sounds like what happened to mine in november
the torque converter is shot, which ruins the rest of the transmission
if pull the trans pan you will find a whoooooooole lot of aluminum shavings, i mean alot!
my rebuild was $1400 and i have to take it back for more work
it seems the shavings messed up my valve body and i think i am going to have to replace the valve body entirely.