2001 Dodge Ram • 175,000 miles

I have a 2001 Dodge ram 1500 Laramie slt extended cab 4 door. Recently bought it in January and I had no idea of this feature. Well, since I have had it I noticed it had a lot of torque and did not shift smoothly and shifts to where there is a rough shift at 30 when it should shift smoothly at 25mph. Now when I turn off the o/d and the o/d off light is on it shifts smoothly and with no torque. Is the what is suppose to do. I researched it and the o/d off is for pulling and with o/d on is for driving, I get the feeling my truck is working opposite of that. How is the o/d suppose to work?
April 27, 2013.

Scan for codes first and freeze frame it but have a trans guy do it

Apr 27, 2013.