I had a couple of service guys work on my gen they'd get it running in front of me and when I hit the road it wouldn't run or stay running under load. I fought this for months!
I finally pulled into a CG and called Mobile RV Repair and told him I was going to pay him to STAY there forever if that's what it took to find out what the problem was with the generator.
He walked right over and opened the gen bay and pulled out the fuel pump and showed it to me.
Fuel pump has a diaphragm, known to fail over time. It starts with a very fine line crack in it or rot starts. That gives you the intermittent problems and then it starts to really degrade. Most don't pull it out and check it.
He replaced the fuel pump and also noticed how much fuel line I had tucked under the MH. Said it was WAY too much line. He cut the fuel line shorter and put in new pump.....been working since.