Did a quick search on here and appears my trans is doing the exactly the opposite than most on here.

When I shift into D or 1 the truck does not want to move forward - like the brakes are stuck or something. In fact it needs a signifigant amount of throttle input to get it to move. I jacked up and spun each tire with no real effort. Also if I shift to reverse it moves like normal with no throttle input.

I don't want to drive it until I look it over but any suggestions on what it could be other than the obvious need for a rebuild? (has 160k total and just 50k on rebuild). Something to do with the transfer case or converter possibly?

Fluid appeared ok, but plan to change (along with filter). Any ideas or similar experiences?

Starting to put 2 and 2 together....

While under there yesterday I noticed the drivers side of the engine and undercarriage was a bit "wet". I had an oil pan seal leak awhile back and figured at first it was that...however ran my finger across a couple drops and it came back fairly clear and no strong odor. Was thinking p/s or brake fluid...now thinking it could be trans fluid.

Any idea on where to start looking? Some place it could leak AND affect the transmission?

This condition is very similar to the "tugging" listed in another thread but does it mostly at idle. Feels like i'm hooked to a good size load.

Thoughts????

You are facing low transmission fluid.
You might need to change out the transmission fluid and filter.