engine shudders, power loss and loud knocking

Took 2014 Ford Flex into Ford in March 2015 because it had a significant loss of power, to the point of scary dangerous when getting on the freeway. I had the oil changed and when I changed it the guy had said, wow your coolant is low. He said that's not normal in a car this new, Take it to the dealership and the warranty should cover it. Ford talked to me like I was a total moron and said nothing was wrong. After my car broke down and was no longer drivable, Ford agreed to replace the Engine but they tried to allow my warranty to run out. It took them 3 months to agree it was an Engine Issues that occurred in the manufacturing plant with the 4th cylinder shaving off metal pieces and they were in the engine. Ford replaced it and now it is again having problems. THis was months of BS that I just minimized for everyone's benefit. I was so pissed I posted on social media and got their attention but now I have more issues.