Well with only 53,000 miles I retract my statement about the timing chain, unless it jumped a tooth? Maybe check the timing with a light, could be the distributor. And a vacuum guage can be helpful in diagnosing an issue.
Your car is 42 years old and those things come with age more than milage but you now can enjoy the ride. Wonder what the cars made today will be like in 42 years ? :2_thumbs_up_-_anima
I remember once camping in central Iowa at a large lake. My wife was walking and sunk waist deep in some mucky looking stuff. She paniced when I said I was gonna leave her there! Like a fool I helped her out!