Funny thing - I (literally) dropped my Hurricane 35M off at a Ford dealer yesterday for the exact same issue with the P0300 check engine light code. My check engine light wasn't blinking either when it occurred on a recent trip. I cleared the light with my OBD scanner, and the Ford service tech said that they would prefer that I hadn't done that, since it makes it harder to track the problem down. Even though it cleared the check engine light, there is still a record of it in the engine's computer, so that may help them diagnosing the problem.
I also had issues with a hanging brake caliper (brake dust on the tire and a "chirping" sound when the steering wheel turns to the right), so the Ford dealer is dealing with both issues simultaneously.
The nearest Ford dealer for me that could handle my coach is about 40 miles from home - only a minor inconvenience for me.
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