I have a99 BMW 528i 6 cyl. It Wil not throttle up. Only about 2000 rpm and idles a little rough , what do think.

First two most likely suspects: 1) A big crack in the air tube that runs from the air filter to the throttle body. 2) A failed mass airflow sensor.
You should get a check engine light which will store a trouble code. However, there is no trouble code for "massive air leak in the intake tube", so if that tube has cracked, the code will point to some related sensor or system.