RD500 fuel problem

Any ideas appreciated please...
My RD500 will start fine on the choke....as soon as I back off the choke
however, the engine bogs down at almost exactly 3000rpm. Above 3000, it goes
great.
If i turn the choke back on, it sort of idles, at around 2500rpm....
No overheating, no strange noises, it just bogs down at 3000rpm, then goes
like a rocket as soon as it clears!
thanks for looking.

 >Any ideas appreciated please...
 >My RD500 will start fine on the choke....as soon as I back off the choke
 >however, the engine bogs down at almost exactly 3000rpm. Above 3000, it goes
 >great.
 >If i turn the choke back on, it sort of idles, at around 2500rpm....
 >No overheating, no strange noises, it just bogs down at 3000rpm, then goes
 >like a rocket as soon as it clears!
 >thanks for looking.
 >
 >
check every rubber and plastic part, especially the gasket
from the carb to the intake manifold. make surre the carbs
are squeaky clean, every little passage. make sure they are
set right. check the air filters, too.
if all this fails, do the line tests on the stator.....make
sure all the ohms are right.<!-- ~MESSAGE_AFTER~ -->