Anyone here ever had a dealer not be able to fix their car? Strange issue with my Lincoln MKC

2015 Lincoln MKC w/ ~ 17k miles, leased new in Jan 2016 (18 months ago)About 2 months ago the car started running rough at idle, within 1-2 days the check engine light came on, followed by the wrench light - called the dealer and booked an apt for the next morning. Ran the in car diagnostic and it came up clean. Lights weren't on the next morning, dealer said no codes were found in the system and couldn't replicate the issue over the 2-3 days they had the car.Fast forward to last week, car is running really rough again, damn near jostling my head while idling at lights. Almost stalls out and i can see the RPM gauge keep dipping to 600-700rpm, then back up to 1k. No CE, no wrench light.Back to the dealer last Friday, I asked the tech to sit in the car with me and he confirmed something was definitely wrong. They called me twice this week to say they changed out two parts with no luck, still running really rough at idle every time they start it up.They contacted Ford/Lincoln in Detroit and have been troubleshooting, but said they are stuck and don't yet know what the problem is.So - uh - what happens if they can't fix this? Anyone run into this before?Looks like it may qualify under the FL lemon law if they have the car more than 15 days or in 3 times for the same problem (currently at 10 days, 2nd visit) - but i just find it odd they can't figure this out. via /r/cars http://ift.tt/2sGZZVG