I have noticed something with my transmission shifting problem. If I re-set the computer by disconnecting the battery for 30 minutes, the transmission shifts fine. However, when I turn the ignition off and crank it back up, it doesn't shift into 3rd or 4th gear. This thing is driving me nuts. Has anyone experienced this? By the way, I dropped the pan today, no metal particles on the magnet. I refilled it with ATF-4 and a can of TransTune, but I still have the same problem.

If it is a computer problem, where is the most likely culprit located/

 

I have heard of this happening in Dakotas never experienced it in a Ram. The 30 minute battery rule works but you need to drive the truck for at least 60 miles to reset all of the paramiters and reteach the computer how you drive. If that doesn't help then I would start looking at electronics of the transmission.