This perhaps has been talked about before and I think it is a problem we all experience with these aging cars.
Recently I have had overheating problems with Miss Daisy. Traveling 10 miles was ok as long as I kept her to 40 mph, but that has been getting worse and worse and when we hit temps in the upper 80s that distance was around 3-5 miles.
I tried the vinegar trick with many flushings that did little. It got so bad that I did a wedding where I had to travel 5 miles to pick up the bride, and the temp rose to 200°F. Then I had to travel about 10 miles through town to the event. Luckily, I made it, but as everyone left, I noticed I left a trail of water. What I did when I got home was I bought one of these: Cooling System Flushing Gun - Welzh Werkzeug. You hook up your garden hose and your compressor. I backed flushed the radiator and was amazed at the chunks that came out of the radiator filler. I then was able to drive her to a car show 10 miles away in 88 degree temps and the car temp stayed at 185. At least I do not need a new radiator and it was an easy fix.