Thanks for all the help guys...
Ken, I went back to the 72 Jet... I am not sure I understand what you mean about drilling the carb slide.
So far I can say it happens regardless of jet size (I started with a 74, went to a 72, 70, then 68 and back to the 72), spark plug size (I started with B7HS, went to a B6HS, then back to a B7HS, tried a B8HS and now back to the B7HS again) I changed all my fuel, didn't help. I run premium 91 octane and add an Italian synthetic 2-cycle I got at the local vespa/snow mobile shop. I took off the air filter to see if it was not getting enough air. It started when it got humid in Omaha, but weather has gone back to like when it was running great and still having the same issue.
Mel, I would hate to think that the brand new petcock filters and rebuilt carburetor would already be having trouble, but the tank does have some rust, and it was cleaned out as best as it could be. I've only had this Maxi for a little over 3 weeks and we replaced everything!
I'll drain the fuel again and pull the petcock and see if it has anything clogging the filter screen, and I will pull the banjo filter and see if it may be clogged too.