Okay. Just spoke to the Man. Sorry for the delay.

He says, and three others of us seem to agree, that the "sluggish" would have been the car's computer going to "limp home mode", which runs the engine at a maximum of 30% power, to help you move out of danger without causing engine damage.

And to ask your mechanic to check the oil pressure sensor, as if this came out (it does happen), you won't get a warning light, but the engine will drop oil pressure, which the computer will pick up on, putting it into limp home mode. The smoke would have been oil falling on the hot exhaust.

Let us know what your mechanic says. x