Well I know you didn't ask, but during the Amazon years Volvo often ran full page newspaper ads headlined "27 mpg city guaranteed!" without asterisks or disclaimers about driving habits or transmission type. My three did it for 30 years. There were glitches when worn linkage interfered.

Check the yokes on throttle shafts (where linkage meets throttle shaft yoke).
Check ends of linkage rods for roundness, where they ride in sockets.
Check every point in linkage where metal meets metal.
Wear in the linkage can cause squirm and lag in its action, interfering with synchronization and causing frequent need to tinker with carbs. You should be able to set them and forget them. Shot linkage will keep you busy chasing your tail everywhere around the system. New linkage parts are cheap and they pay off big.