Town and Country transmission problem

When backing up in reverse I come to a stop and shift into drive. About 60% of the time it slams into gear (Drive). It feels as if someone rearended me.
It’s a 2012 Chrysler Town and Country with 40K miles. 2 dealers worked on it, reprogramed the computer and replaced 2 seloniods and the problem is still there. They have no idea what is wrong but sat thats typical on that 6 speed. Can anyone help me figure out what to do next?
Thanks
Mike

Dealer is aware of issue with other vans? So, problem cannot be fixed with replacement trans? Because they ALL slam into gear? A new trans would not perform differently? According to dealer?

Ask the tech to make sure the idle speed is correct. And that the transmission fluid level is correct. I doubt this would be the case at 40k, but if the owner’s manual says a routine maintenance fluid and filter change is due on the transmission, schedule to have that done. I’m assuming you’ve never done a transmission flush or added transmission fluid on this vehicle. If so, that could possibly be the problem if it was done incorrectly or the wrong fluid was added. Other things that can cause this is play in the post-transmission drive train. For example, if this is a rear wheel drive vehicle, the drive shaft connections and/or the differential might have excessive play. (There may be a recall for this vehicle apparently about the right rear wheel hub/bearing ass’y, so ask the dealer if that could be the problem.) If a front wheel drive car, the CV joints could have excess play. Faulty or worn engine/transmission mounts could also be a cause. If you don’t believe this is actually “typical” or “normal” – which could be the case, so make sure — besides the obvious like checking for diagnostic trouble codes, those are places to start.