I dont recall much to this movie and I might be confusing two different films. I watched it in the early 2000’s on cable tv. I believe the main protagonist has suffered some painful loss and starts to wander aimlessly in his persuit of death and encounters strange people along the way. The only scene I am certian of is he is wandering down the side of a road and see’s a man in the distance trying to knock down a road sign. When he approaches the man the sign reads do not pick up hitch hikers, mental institution near by. The stranger is clearly a patient pretending to be a fellow hitcher that cant get picked up because the sign, which he finally tares down. Both men finally get a lift and shortly after the mental patient and the driver discover they like doing impressions and the driver keeps doing an impression of howard corsell. It gets so obnoxious the main character demans to be let out to flee the duo’s painful game. I believe the ending to the movie is with the main guy entering a building and closing the door, the camera pans back to reveal the building is a test site for a military bombing range.
Good luck with this one I’ve been trying to find it for while.