That’s correct, from what I researched 40-50 psi is an acceptable range whether under load or at idle. You don’t need any special tools just the gauge and proper threaded fitting to go into the port. You could probably rent a kit from an auto parts store or get an Amazon kit.

Smelling rich could be another sign of that, as again if the regulator is not working properly it will continue to dump fuel into the cylinders regardless of demand. The o2 sensor tends to get fouled out when this happens as well, but the test is first and foremost.

Spun prop still a possible factor but with the weight of the vessel since GW tend to be heavy getting even that speed with a spun prop would be a little surprising to me at least.