thom wrote:

I changed the fuel filter and that seemed to fix the power problem
once I got under way again.

Then on the way home, it did it again.  Now i was stumped.  When I got 
down to about 40, I stomped the pedal up and down a couple of times in
a hissy fit, and the bus took off!  
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try banging on the carb with a wrench.  SOunds like the float valve or
something is clogging.  If that helps, then I'd take the carb off and clean
it out thouroughly.

my two cents
clara