rough Idle and get so low it knocks off while driving?

Hi Terrence,

Yes, the engine can knock when the idle speed gets too low, I would check for vacuum leaks and service the throttle body and idle air control valve, here are guides to help you fix it:

https://www.2carpros.com/articles/throttle-actuator-service

and this guide use when the engine is cold only:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/idle-air-control-valve-service

Check out the images (below). Please let us know how it goes.