I think that 'whatzitznutz' is called the purge valve solenoid.
The little research I did though indicates that it could still be (in order of likelihood):
non-OEM gas cap
Cracked evap canister
split hose or leaky connection
purge valve solenoid
wiring harness or bad connection
I still get the P0442 code on the Amigo regularly (but only when the fuel drops below 1/2 tank). I'm running an aftermarket gas cap but should probably switch back to the OEM since the replacement didn't fix the problem.
The US.RV shop manual has pages & pages on the subject. It just hasn't bothered me enough to try & chase down that gremlin yet.