preachers daughters 318i is in big trouble

As long as she has had it it has had a problem with the idle surging sometimes when she'd first start it but once it warmed up or was in gear it would run fine. Then the other night the suging became constant and stronger. After a couple of blocks the motor became extremely loud and rough, and there is almost no power in any gears. She will be taking it to a shop, but I wanted to have some idea of what to expect to hear. I wouldn't want to replace the motor if it needs a new hose. I'd just ask God, but I bugged him last week about my riding mower. :)

Any suggestions?

1985 318i
4 cyl 5 speed
I think its a 1.8 L
and it has a timing chain rather than a belt.

Thanks in advance for any thoughts you might have.

Reverend James B Jones
Seattle Washington