Hi all. I had this issue twice when I owned my cougar.
First time we worked out it was the battery. It was past it's used by and everything went nuts. The banging felt through the steering wheel was the
ABS system.
Second time was while driving on the freeway, i started to get lights flashing and revs dropping, along with the banging. Worked out to be a bad batch of fuel. I also changed the fuel filter (located under the drivers side just infront of the rear wheel).