This is going to sound pretty pathetic, because I have no details - actors, director, date, or even plot. I saw it a long time ago and remember loving it.
At a very rough guess, I would say it was made sometime in the 80s or 90s.
It involves two men travelling around the US in trains, buses etc. It is definitely NOT ‘Planes Trains and Automobiles’, though, (I saw this the other day).
I think one of the men could be a convict or escaped prisoner and the other is somehow in charge of him - anyway I seem to remember that they are forced into each other’s company and begin by hating each other.
There’s just one line of dialogue I remember - they are sitting in a bus, and one says to the other: "I have just two words to say to you: ‘shut the fuck up’ ".
Quite understand if you can’t help…