My 3205 that has the same engine as the 2086 had an issue with the igniter (ignition control box). It would run fine but when the engine ran at normal operating temperature for 30 minutes it would start to misfire. I ended up replacing the igniter and my problems went away. The FD620 was used in a lot of machines so there are lots of people selling this part.
Cub Cadet sells this part with a little mark up!
https://www.cubcadet.com/en_US/cart
This is more like it....
https://www.amazon.com/s?k=21119+215...l_4agremnt0i_e
https://www.walmart.com/ip/CDI-Box-I...2157/957588658
Has your machine had the cam gear replacement yet? This has nothing to do with your issue but something to be aware of.