Small Engines (Lawn Mowers, etc.): Troybilt tiller with 7hp Kohler, rust problems, engine stalls

Question
This is a 30 yr old tiller. It idles fine but won't run under load for more than 10 minutes or so and then it starts coughing and ties to stall. If pushed back to idle it idles fine but won't take more throttle. It has new points and condenser and plug and air filter and the carburetor has been cleaned and the governor set according to the manual. The coil is two years old.
What do you think I should check next?
Thanks.  

Answer
Hello Dan:

1- Check the Gas Tank Cap. Ensure it is Venting the Tank Properly. 2- Check the Inside of the Tank and Make Sure there is No Loose Rust that will be Drawn Towards the Outlet Port of the Gas Tank. 3- If the Cap is Venting and there is No Rust Problems, then Check the Compression when the Engine Stalls. With the Engine Hot, BE CAREFULL, PLEASE. If the Compression is Not Above 100psi with the Engine Hot, then a Ring May be Stuck or the Engine May need Replacing. The Valves May Require Reseating or Adjusting. Did you Soak the Carburetor Overnight in Carburetor Cleaner? Did you Blow Out the Passages with Compressed Air? Hope this Helps. I am Here if You Require More Assistance. Let Me Know What Happens, Please. Thanks.

Good Luck

Respectfully  

John