Just passed 80k miles, never had any problems. Today while driving, they engine nearly shut off, and is running very rough. Code p0300 is showing and saying multiple misfires. When I step on the gas, the rpms don't move at all. Taking off, it barely shifts gears. Never encountered anything like this on any car, esp the rpms not moving. I changed the plugs, and it didn't help. Does anyone have any idea what this could be? The check engine, low tire light, and traction control lights are all on. Thanks for any advice.

 

I would take it to Mazda for diagnosis, purely because their scan tool has a far wider range of codes that are recognised.