Check the linkage between the carburetors that connect the throttle butterflies. The butterflies MUST open and close at the same time. You DO NOT want one butterfly closed and one ever so slightly open. Do they open fully (horizontal?).
Did you re-connect the throttle cable?.... Yeah, things like that happen to the best of us!
If the above are as they should be.... are both carburetors accessing the gasoline flow? Yeah, that happens too... float upside down, something restricting the gasoline flow. Let us know what you find.
