Hello i have a 98 ram 1500 5.9v8 thats experiencing some odd tranny issues. i searched the web and a few forums sifting through other peoples tranny issues but haven't found anyone experiencing what i am. what's going on is when the truck is still cold it shifts into drive just fine.But after coming to a complete stop at a stop light the rpms will drop to 400 and then raise up to idle like the engine almost died but it never dies. after this the tranny feels like its in neutral with no response but the gear select still in drive. if i rev the motor it will then kick the tranny into gear hard depending on rpms. if the stoplight is red long enough then the idle will kick the tranny back into gear, but almost kills the engine again. also this problem is accompanied by erratic shifts between 2-3, especially if i am going uphill. by erractic i mean sometimes a late shift, sometimes it won't want to shift out of 2nd until i rev it up and let off the gas, and sometimes this one only when uphill it will shift into 3rd perfectly but then downshift back to 2nd then back to 3rd continueing this until the gas is let off or floored. These problems only occur when the truck is still cold. after its been driven and warmed up it shifts fine with no problem.

truck has 160k on motor around 20k and the tranny. previous trany was rebuilt do to the front outer ring gear breaking apart.
no check engine light on either.

thanks for any help