Small Engines (Lawn Mowers, etc.): small engine repair / maintenance, throttle linkage, butterfly valve

Question
There is only one hole.  The carb looks identical to the one I removed.  I replaced the carb because, I filled the tank up with gas in the evening and came out the next day and the gas had leaked out thru the carb and air cleaner filter.  I refilled the tank, and tried to start the engine.  It would run for a short duration at what I consider it's normal speed but sputter then stall.  -------------------------

Followup To
Question -
Taking the advice of my local parts retailer, I replaced the carb on a 2000 / 2001 B&S 6.5 HP lawnmower engine.  When I start the mower, the engine reves/idles EXTREMELY fast.  The carb has NO adjustments.  How do I adjust the idle down?  The throttle linkage and spring is in perfect condition.  They are connected to a linkage on the carb and a lever on the back of the engine.  I believe the lever on the back of the engine is connected to the internal engine govenor but I'm nervous about blindly adjusting the lever.  Any help you can provide will be GREATLY appreciated.    
Answer -
How many holes are in the carburetor butterfly shaft? This is the part that the throttle linkage connects to.  

Did the engine suddenly start to run fast?  Is this why you replaced the carb?

Let me know.
Eric

Answer
Do you still have the old carb?  If so, put it back on and see if the engine still runs fast.

In regards to the butterfly shaft, I put a mower back together the other day only to have is run too fast.  A closer looked reveiled that I had used the wrong hole in the shaft and caused the linkage to bind.

Remove the air filter and see if the throttle butterfly valve is closing all the way.

Let me know if it runs fast with the old carb.

Eric