Routine maintenance gone wrong at dealership?

My 2011 Murano is a cream puff. It only has 102K miles with gentle driving. It has had all the services recommended by Nissan over the past 14.5 years. In turn, it has been incredibly reliable.

I recently took it in for an oil change while on a trip. The mechanic told me my head gasket was starting to leak (nothing too bad or urgent. Just something to take care of sooner rather than later). I went to my local dealership a couple days later for a gasket head replacement, new valve covers, and a brake flush. The service advisor messaged me asking for my permission to install a new air flow meter since the old one cracked from age. I agreed. The service was supposed to take half a day, but ended up lasting all day. When I picked up my car and started driving home, I realized my AC was dead (blowing hot air). I returned to the dealership ASAP and asked them to get it working. A few minutes later, the service advisor returned from talking to the mechanic. He said my AC compressor coincidentally "crapped out" during the seven hours they had my car. The AC never had a single problem in 14.5 years and my compressor just died a sudden death with no warning? Autopsy report: "AC comp with clutch; replace AC compressor with clutch (add evacuate and recharge); has power and ground at clutch. It is not engaging." Before authorizing the replacement, I asked if they had checked the refrigerant. They said the clutch was malfunctioning despite receiving the correct electrical signal. I authorized the replacement. There's a lot more I won't go into here, but bear in mind that the dealership had my vehicle for over a week while playing games with me. I had to address the owner to get any action from the GM. This, sadly, is just the first part of my saga.

I picked up my Murano yesterday and was thrilled that she was back in action and her AC was blowing cold. I live 5-10 mins from the dealership and went straight home. Today I drove to a destination five minutes from my house. At first everything seemed okay. Then I parked for about 20 minutes and restarted the car. It was then that I noticed a very rough idle. While driving to the dealership my engine seemed to be making more effort than usual to accelerate in the range of 40-50 MPH. Then, when I arrived and went to park, it made a very loud grinding metallic sound when I turned my steering wheel. No check engine lights were illuminated. I asked the service manager to sit in the front passenger seat so he could hear and experience the same things my daughter and I did. He acknowledged the rough idle and the metallic grinding sound.

I read about potential causes of rough idling and understand that the new air flow meter and AC compressor (or installation errors thereof) could be to blame. I'm hoping there's a simple answer and solution. However, I cannot comprehend how the grinding sound possibly could be related. All my tires are in great shape; two were installed just a year ago and the others aren't a whole lot older. I have them rotated routinely, so surely someone would have informed me that there was a problem with my suspension. I know cars get old and parts wear out, but not at the exact same time! I would really appreciate your insights as I prepare for another day of dealing with the dealership. I am over $2K in the hole with a car I cannot drive. It is my only vehicle and I cannot afford to replace it. Thanks in advance for your help.