I have a 2016 that had the same symptoms. I had a P301 and a rough start on ignition that cleared. I diagnosed the issue myself prior to going to the dealer. The intake manifold gasket had been compromised somehow but the cylinder pressure was bleeding into the coolant system and when the car was off cylinder 1 would get flooded with coolant. On start up the ecm would identify a misfire. I removed the plug from that cylinder and saw liquid in there after letting it sit overnight. I took a sample out and put it in my refractometer. Sure enough it was ethelyne glycol btw it was red like motor craft. At that point it was clear. Called the dealer and had it scheduled for service. I had it gone for 2 weeks with a free loaner. Thankfully this was at 47xxx. Out of warrenty about $6k. Its a total teardown. Its been running great but im going to get rid of it before the 60k. Sucks because the vehicle handles great. The repair technician chocked it up to being an improperly torqued manifold but im reading about possible casting issues which means it will happen again. Not sure what to do.