Hello!

New to the forums. Searched around but havn't seen much of a similar issue to mine, so maybe someone else could shed some light on what I'm experiencing.

I have a 2012 Cooper S Countryman All4 with 86K miles. I love the car, it's been a blast to drive for sure! I've had it for about a year and 9 months.
I havn't had any issues with it, aside from occasionally feeling a very slight stutter for a half a second during hard acceleration. But this only happened once in a blue moon, so I didn't think anything of it.

I few weeks ago I filled it with mid-grade fuel from my local Mobil station and drove the 2 miles or so back home for the night. The following morning it was in the teens for tempeture so I started it to warm up for 10min or so like I do any other cold morning before work. Didn't notice anything to be out of the ordinary. Started right up, sounded the same, idled the same, nothing odd.
Got in and after pulling out of the driveway it started stuttering and shaking a lot while accelerating. At first I thought maybe the fuel I had got the night before was bad, but it was stuttering so bad that by the time I got to the end of my street the engine went into low power mode with the yellow "half filled - half empty" check engine light in the center of the tac. Also I had a solid yellow check engine light on the spedo that would occasionally blink while accelerating. Once stopped it would shake and sputter while idling. But the condition would stop once you turned the car off and turned it back on. And then return once you started driving.

I barley made it to work about 9 miles away from my home and made an appointment to go into the garage that specializes in German vehicles (primarily Audi and Volkswagen, but they do work on BMW too). The mechanics there read the check engine codes and turns out there was a misfire in cylinders 2, 3, and 4, as well as a random misfire. They changed all the spark plugs and changed the coils on cylinder 1. The misfires stopped, but now we had a new problem, the codes were coming up with something called "Super Knock". They did an oil change (which it was overdue for by 1500 miles anyway) and a carbon clean. Now, the car does not misfire and stutter like crazy, but now it will "buck" (as the mechanic put it) whenever you try to accelerate quickly or give it too much throttle when you accererate. Pretty much whenever the engine is under any big load it will bang and buck and jerk.
On one day it was running pretty well and I pushed it a bit and it went straight into low power mode again with the same half and half check engine light on the tac with the shaking and sputtering while idling. Once again the low power condition would go away after shutting the car down and re starting. I checked the codes and it was reading a misfire in cylinders 2, 3, and 4 again.

Took it back to the garage and my mechanic insists that he thinks it is the timing chain. There apparently was a timing chain recall but my Mini is not within the years that the recall was going on. After doing a bit of research, I've found that my Mini does not have any grinding or clanking or crunching sounds where the timing chain is located like other people with a timing chain problem are having.

I've called Mini and they want me to bring the car in and do a diagnostic for $120...who knows how much it would cost to fix it too.

So my mechanic tells me that all Mini's start blowing up around 80k miles and are basically throw away cars and that I should sell it and he does not want to go any deeper into the internals of the engine to find the problem, since hes so sure its a timing chain and possible damage to the car has been done.
I cannot sell it and finance a new car becauase I owe too much on my Mini, so I am wondering if anyone has had the same issue I have and have any advice on what it could be.
Any input would be awesome.
Thank you guys.