Small Engines (Lawn Mowers, etc.): Sears Snow blower engine speed, speed circuit, snow blower

Question
I have a Briggs 2004 8 hp OHV snow engine. 276034. It starts fine choked, but when you move the choke open the governor causes the engine to rev up then down up and down. The only way to stop this is to leave the choke half closed. Could this be normal? I don't remember this when I bought it new last year. If I use it open while it is fluctuating, it does it less under a load but still does't seem right.  

Answer
This problem is commonly caused by a dirty carb.  Usually you can remove, disassemble and clean the carb with compressed air to cure the problem.  

Since it does it less under load I'd say the governor is working properly and the low speed circuit in the carb is the problem.

Does this help?
Eric