The high revs sounds like an air leak to me. Maybe the N80 valve is stuck open and the other end of the tube is open to air.
The easiest way to check your evap circuit is working correctly is to listen for a 'whoosh' pressure relief noise when unscrewing the petrol cap, when the tank is nearly empty.
If you don't get that noise, the evap circuit has a leak to atmosphere somewhere, or the N80 valve is stuck open. Quite common.
Brimming the fuel tank is not an issue with a nicely sealed evap circuit, that's a myth.
Fixing it once and for all does usually entail a new N80 and a new carbon can in a lot of cases. The carbon can breaks down over time and little charcoal pellets can get sucked into the N80 valve, causing it stick open.