Go to jamies nsr site (see the links page on this site) and goto the technical section. there is a wiring diagram done by Andy, the top bloke that runs this site, for the '21. Check and see if there is any power going to the pgm from the pickups on the alternator and check that all male/female connections are tight. I had a persistant missfire on my '16 due to a poor connection.

Best of luck as pgm's aren't cheap I'm afraid. Sorry.

P.S. welcome to the site
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it's a name, not a condition