96 ram 2500 Down shift ?

I have a 1996 Ram 2500 , V8 5.9L Gas Auto trans.
I just bought this truck and it seems that it downshifts much to easy... and I also do not see a way to prevent it from going into overdrive!
as soon as I give a little Gas , It comes out of overdrive and most of the time will also downshift into 2nd, then upshift right away! it has been set up to haul a 5th wheel trailer and this may have something to do with it. I would like to resolve it if i can !!
Thanks for any help !!
Tommy

Try adjusting the TV (throttle valve) cable. Here's a link on how to do it. http://jcj.net/dodgeram/trans_adjustment.htm

Danny

Danny, Thanks for the input !! I will give that a try tomorrow