Bought one of these a couple years ago to travel with the camper(in storage right now and I don't have access) . Just bought a second used one, because it was super cheap. This second one fires up and runs fine, but when I switch on the ECO button it doesn't idle down(nothing plugged in). I swear my other one would idle at a lower speed when you let it use the ECO function, but its been a while since I've used it. Any help? I already cleaned the carb good, anything else to look for? Thanks

Dirty contacts on the eco mode switch, maybe?

You might try pulling the control panel off to see if the switch is still plugged into the wiring harness on the back, and if you can get a spritz of WD-40 on the switch contacts.

make sure the idle control switch that is on top of the carb is clean, working and installed properly