Overdrive problem, 99 Ram , 5.7L auto tranny

I have a 99 Ram Quad Cab 5.9 and it acts like it dont want to shift out of overdrive unless you take it out of overdrive or put alot of pressure on the gas and kick it down a gear. It acts sluggish, even though it was in for fluid change 30 days ago. It happens more when cold then warm. Fluid is good color and the truck has 96K on it.

Any Suggestions? Sensor maybe?

look in the relay box under the hood and find the trans relay.there should be a line of relays beside the trans relay swap the trans relay out with one of the others just remember which one.now see if the trans acts any better.if it does get a new relay and swap the one back and put the new one in trans relay slot.