OK!!! I lowered the tank about 3/4 in. and VOILA!!! the problem was solved!!!
Heres the thing!! The manual photos of the engine and tank mounting (showing my engine, the OS 91 FS, show the tank mounted in the hole provided thru the firewall.
Guess what, thats tooooo high, causing the engine to flood while just siting there and also to run incorrect while flying.
Yes, I tried to lean out the mixture while idling and it helped, but it became tooo lean in the air, shutting down the engine.
I suggest that anyone mounting the engine inverted and installing the tank in the hole provided in the firewall NOT DO SO.
Lesson learned, DO NOT ALWAYS GO BY THE INSTRUCTIONS IN THE MANUAL
GREAT PLANES better think about this!!!