Transmission: slipping, chugging/tugging. Cruise on or off. Seems like it’s not sure it should down shift.
AWD or FWD?
Is the check engine light on? How do you now it is the trans slipping and not something else? Have you ever had the trans fluid changed?
Have you kept up on trans fluid and filter service?
As we have seen multiple times in this forum, many people seem to attribute engine problems to their transmission.
If not, that long-delayed, vital service could be the source of the problem.
I think that you’re assuming too much. As others stated, there are a number of things which could cause a chugging sensation. One misfiring coil for example. Or a partially plugged fuel filter for another.