I have a 04 RXP stage 2, ran good all last season with all mods. Then late in the season started missing with rpm's jumping up and down.
I took it to the dealer, they checked compression, fuel, spark, and the cam, and still came up with nothing. They said the rear cylinder isn't fireing. Just wondering if anyone has any ideas.

I had the same problem. No one could figure it out. Changed the spark plugs. Runs fine.

And if the plugs doent help, change the coil on the spark plug thats not firing.

ALSO U CAN CHICK THE CRANK SINSOR IN THE PTO OR THE MAIN HARNNISE