Confused Shifting

[nghtshd88]

54k miles- my trans is starting to act up. When shifting 3rd-4th gear if I am light on the gas on an incline it gets confused and toggles between both until i either lay off or give it more gas. I also notice a humming noise at the start of 5th now. Not sure what that means

I assume solenoid pack? I have no other issues. No banging or harsh engagements.