my 5.9 quad cab has no power from 50-60-mph in but when you get above 62-65 it runs great . i was think mabe converter since it has 150000 on it ... any suggestions

 

do you mean the gas pedal seems dead. you mash the gas and nothing seems to happen.. downshifts frequently when cruise contol is on.. replace throttle position sensor (tps).

 

How many RPM's are you turning when you are having this problem? What gear are you in? A "dead" spot is usually related to a faulty TPS, but it should have more to do with the amount of throttle you are giving and the engine RPM, not so much the speed you are going when you have this problem.

 

As silver said what are your RPM's, ??? Mine when stock with 265/75/16 the rpms were just low enough that it would kick out of O/D to pick up at that speed. If they are around 15-1600 than it is hard to get going in O/D

 

Yeah, sounds like just a transmission issue. It all depends on RPM's, the stock shift points, and gears. I forget where my dead spots are, but it happens. You are running at too high of an RPM, so the tranny wont downshift, such is a problem with automatic transmissions. Just gotta deal with it. An aftermarket torque converter can definitely help, though I am not yet sure of what is offered for our trucks as I'm still new to the Dodge Ram thing.

 

rpm are around 1600 ,, acts like it should downshift but dont ,,,,and if you give a little gas the valves seem to chatter but if you give it enough gas to downshift it is fine

 

the chatter you hear is most likely spark knock, or pinging. when the engine is doing this its working against itself, and has little power. see this.... https://dodgeforum.com/m_653102/tm.htm
sometimes its overcome by premium gas, others have a badly leaking plenum.