I have a Troy Bilt pony with a intake that simply wont stay tight. Every time it comes loose, I get surging. Maybe check for sucking air between the carb and engine. I usually check that stuff by spraying carb cleaner in the suspect area to see it is changes the RPM.

I removed the gas tank & found that the Gas Tank Shut-off valve, was not working correctly. It didn't turn off the fuel as well as restricting the flow. The tank was pretty dirty inside, I took a shop rag cleaned the inside & removed the valve. There were so many sediments on the filter where only the very top of the screen let fuel flow. I also changed the points & condenser. I think the condenser is original one that came on the tractor because the black paint from the engine & on the clip was never separated and it is very corroded. I also cleaned the Vacuum Filter which was not restricting air flow, since I was on a roll I kept going.

I have a new fuel valve and filter on order when they are installed I'll see how it runs. These are all issues that needed to be addressed and I should have done so before, but the tractor was running Good & I'm of the mind set... "If it ain't broke" ....

Again all your replies have helped.

I hope you ordered a new bung for the valve/filter to slip into as well.

UPDATE: I re-installed the Fuel Tank & Original Walbro (after cleaning), Carburetor. Re-placed Fuel Valve/w filter & Hose, Points, Condenser and Plug. I believe it was a combination of issues, mostly the carburetor needed a good cleaning. The Fuel Tank Shut-off Valve was faulty and filter needed replacing. Perhaps, the Points, Condenser and Plug did not need replacing but it is good to know they are new and all gapped properly.

It's Running fine again.

Good to hear, a spic and span fuel system is always the best medicine
for a good running machine. Thanks for the update.

Ken