2001 dodge durango engine rpm's are fluctuating up and down. what could be causing this and could this cause the transmission to shift eractically

Quest#1 Your intake manifold is leaking
Quest#2 Yes
Spray carb cleaner while running at intake manifold gasket , both sides, and check for a difference in running condition while spraying to confirm leak here. Replace all intake manifold gaskets and plenum gasket.
If this does not confirm intake leak , have the Throttle Body cleaned manually by a professional, or yourself using specifically" Throttle Body Cleaner "