Onan MicroLite 2.5 LP series L

Final (I HOPE) update. After further diagnoses, they decided that it was indeed the magneto causing the problems. They replaced the magneto. They said they ran it under full load for 2 hours and it never missed a beat. They said it was ready and to come and get it. Went the 90 miles picked up the unit and brought it home. Installed it yesterday morning and to my surprise it would now only run for 2-3 seconds before it would completely die. Would start right back up, miss severely and die again in a couple of seconds. Not so happy now! Almost seemed like it wasn't getting fuel so I pulled the LP tank off the grill, with regulator and hose, and hooked it to the generator. Same thing. Called the service manager and expressed my anger and then calmly discussed the issues. He requested I bring the entire unit to them. Got up early this morning and took the Sprinter to them with the wife following behind in the car. They got it in and supposedly diagnosed the new problem to a bad spark plug! Replaced the bad plug and they said it ran fine. We went back to the dealer to pick up the unit. Started the unit and it sounded fine. However not all was good. Now the light on the microwave was flickering like the generator wasn't putting out "clean" power. Also noticed that the gen wouldn't supply enough power to run the A/C and the microwave at the same time, which it had been able to do in the past, although it would really load the gen to do it. I requested that they hook the unit up to their load bank and show me that it was putting out it's rated output. They said they would but it would be late in the afternoon before the generator tech could get back on it. The wife and I went bumming around till 4pm. Went back and they were just finishing putting the seats back over the transfer switch. He had taken a picture of the load bank gauges and it showed it was putting out fine. Still won't run the A/C and microwave at the same time, but I can deal with that since it is at the generators maximum output to do that. Curiously, the light no longer flickers on the microwave. Also noticed my torque marks on the generators mounting bolts were no longer in line. I think they removed the entire unit, and did something to it to cure it's issues besides just replacing the spark plug. I guess it doesn't really matter, at least it now runs.
Thanks for all the replies and suggestions, and sorry for the long post.
Bob