cv742 loses rpm then backfires out the exhaust then runs great for 20 minutes then does it again

[dean harness]

kohler cv742 lose rpm then backfires out the exhaust then runs great for a while then does it again

 

[geelee]

most likely a bad ignition coil, very common on that engine. would use 25 707 03-s coil kit. cheapest way to get both coils