Is it the transmission?

I have a 2000 Dodge Durango,automatic transmission.When I accelerate and the car shifts gears,I notice a little push and feels like its taking some extra “umph” to do so.It makes a noise like, if the car is parked in neutral and you pump the accelarator.Is it the transmission going bad?

I have already done the fuel injection service and the transmission service,but the problem persists.