Small Engines (Lawn Mowers, etc.): idle surge, carburator, line leak

Question
i have a 2000 17.5 murray with briggs engine all of a sudden it idles slow then fast , will idle ok if i pull choke a little. can you tell me what it is? fuel line leak? filter not letting gas thru? other? help

Answer
 Hello David:

 From your Description I Suggest the Carburator be Cleaned and Rebuilt. Saok the Carburator Overnight in Cleaning Solution(Gunk carburator cleaner) and then Blow All Passages Out with Compressed Air. Install Kit. By using the Choke you are Compensating for a Restriction in the Main Jet of the Carburator by Pulling the Required Fuel through the Choke Jet as well as the Main Jet. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John