2012 III- Engine shake and rattle

Hello, My 2012 III has 230k, regularly maintained. At start, the engine rattles and shakes. This happened a few times since new, eventually smoothed out but didn’t last. Check engine lite on this time. Any clues? I don’t know if it can make it safely a quarter of a mile away to get it read from Autozone. Am afraid the engine may be conking out.
Thanks for any input.
Ed

 

Hi again,
I finally took it to Autozone to get scanned. The report is as generic as it can be.
Code P0300
Random/ Multiple Cylinder Misfire detected.
Cylinders 1-3.

That’s about it. So you really sure it’s the head gasket? I’m willing to get it fixed to a certain dollar amount. The car is in good condition otherwise.
Thank you!

 

By the way, don’t know if I mentioned this. All fluids seem fine. I kept reading about coolant issues. There’s more than enough, no leaks whatsoever.