These two perhaps?
I recall enjoying the Bob Monkhouse chat show, probably late 80s, when he would showcase various comedy legends. One that sticks in the memory was an American duo of advanced years whose act revolved around one of them speaking incredibly slowly with loads of painful pauses between words, and the other finding this so frustrating that he would constantly jump in and attempt to finish the sentences, with hilarious consequences. It was a great act and Bob M introduced it as a classic that they were re-creating after many years.
Does anyone know who the comedians were or anything about the act?