2001 Durango, 4.7, 2wd, 178k miles. Just changed the fluid about 5k miles ago. No problems until recently. Under more than half throttle, the engine will rev, sit at whatever rpm (say 3k) for about 5 seconds or so, then shift to the next gear. If I'm easy on the gas, it shifts no problem. Fluid is full, doesn't smell funny at all. It shifts funny into all gears, but it seems worse into 3rd and 4th. No check engine light or od light. Any thoughts? Thanks!

Maybe swap out the solenoid pack?

Make sure the cable or linkage for the kick-down still works as it should. I fixed a late 90's 1500 that was headed for the repair shop with a can of PB Blaster and some patience getting it to work again. It's an easy place to start!

Not quite the same symptoms but close would be a bad TPS sensor. Basically the transmission is getting bad throttle position information and does not know what to do. I had this problem on a 5.9 Durango... fix was pretty easy. An external part of the TB with pigtail and connector.