I had the same issue. Started out as a slight delay from 3-4, but at normal operating temp it would be normal. Gradually got worse to where 3-4 would have a second or 2 lag then slam pretty hard. At that point, shifting into reverse either gave me a "shift into P, then R" message or would have a delay then slam into reverse. I was able to limp it back to Dallas from AZ. The dealer dropped the transmission pan and noted burnt fluid and metal shavings, and immediately ordered me a new tranny/cooler/lines/etc. If anyone reading this has any similar symptoms, have it looked at ASAP. Luckily Dodge City of McKinney only had my rig for 2 weeks.