Grey Sludge, engine shake, rev bounce

Hi guys, this is my first post here, i’ve been searching around but i cant really same to find anything with the exact same problem i have.
So i just bought a mini cooper s 2008 and it has a few issues with it, so on the drive home it seemed pretty fine but it was lacking power, but we drove it home anyway thinking we could drive the fault out to identify the problem. The engine management light came on and it still does not show any problems. If i put the accelerator half way down the car will go all the way without an issue but if i put my full foot down the car refuses to go past 3K revs. The engine is abit shakey, and before i parked it up the revs started to bounce on idol. The car defo did not do this before the coolant light also came on so i went on to check the coolant and there is grey sludge in there ? Any ideas what this could be ? I was thinking maybe the coolants have been mixed and i think its called the oil cooler is doing this to the car? Am i correct in thinking so. I would appreciate someones input as i love this car and always wanted to own one ! The car does sound fine though, there are no knocks or bangs, and it has 84,000 miles on the clock.

to add to this the panoramic roof goes to open but then closes what could this be ? I know its a lot of problems help me guys please