LR 90 11j misfired then lost all power…

Hello!

my LR 90 has just, over the course of five miles, lost all power. Injectorsmstill working (AA man checked) but couldn’t work out what was causing it. I can start her up, rev, but not move the car. Black smoke coming out and the whole engine shakes - originally thought it was a misfire but it’s worse than that. Last serviced in the summer…

any thoughts on what it might be?

thanks!