I'd suggest looking at the model# again and posting the correct one.
You've missed/transposed or?? some digits.

With the correct number, we can determine which carb you have.

How does it operate at igh speed under load?

�Bolens 11A-584E765 (2005) Push Walk-Behind Mower

The engine goes high throttle then goes back down. Up and down

Need the ENGINE #'s
http://www.outdoordistributors.com/Briggs_And_Stratton/briggsmodelid.html

Possibly it's a Briggs-
Model: 10H902
Type: 0285 E1

IF SO-
Download the IPL from the Briggs website.

Replace part 394 on page 4/10
Briggs PN 495770 DiaphragmâÂÂCarburetor

IF this is the correct engine, the entire carb can be found here amongst MANY places-
http://www.rcpw.com/briggs-stratton-parts/genuine/699660.html

Just Google Briggs 699660