Where does that hose terminate?  Mine is not cracked, but it's soft and
the cover is gone from the last inch, so it needs changing.

is the check engine light on or flashing? if it flashes thats a misfire and
it could very well be caused by bad coils. we had a whole run of faulty
ignition coils on these cars. you didnt mention what engine you have, though.
its not the 4cyl 1.9L  is it? i dont even remember if they offered that still
in 2000. if it is a 4cyl, check the vaccum hose going to the front of the
manifold , above the oil filter. they always crack and cause a lean mixture,
rough running, and stalling, although ive never seen a light come on for that.

i dont know any common causes for the asc light to go on, so yeah you really
should have the codes read out

Yesterday when starting up my 2000 Z3 (3 hours since last running) The
"check engine" light, the EML light (electronic engine output), and the
ASC+T light remained illuminated and the engine began running extremely
rough. It seemed like 2 or 3 cylinders were variously misfiring. Not
100% continuously, but frequent enough to severely limit any
acceleration, and provide not even enough power to hold 50 mph. I
barely made it home. After cooling its jets in my garage for an hour I
restarted it and the EML & ASC+T turned off, but the check engine light
stayed on. However, the sputterring and misfiring completely stopped.

This Z3 has only 25,000 miles, but I know things happen prematurely.
Question is, WHAT is happening?? I have not yet taken it in to have the
fault codes read, but plan to.

So what do you think-?
- Oxygen sensors?
- emissions modules?
- ignition controls (??)
What?

Jerry