M20b25 Rough Idle. Whole car shakes

[BMWe3O]

Hey everyone,
Finally got the e30 running, but it is not running great... It starts up and idles up and down between 500 and 1000 RPM, and the whole car shakes like crazy. When I rev the car up, it sounds perfectly fine and the shaking stops. Any idea as of what this might be?
Thanks

[Mook613]

Surging idle is most likely a vacuum leak. Have a smoke test done to find where all the leaks are and replace the hoses.

The shake can be related but may also very well be worn engine mounts.

First get the car idling smoothly and re-assess if the shake is still that bad.