Tecumseh tvm220 ?

I have a tvm-220 10 hp engine on snapper mower,starts up runs good sitting there,under load engine will almost shut down at times under load.Things ive done,cleaned carb,new kit 2 years ago.Ive tried adjusting carb.several times but after few minutes it will do it again,this is just under load.will run in shop all day.have this as 2nd mower just in case but hardly gets used.Sure it,s gotta be something with carb,but im missing something.by the way always keep fuel treatment in gas and only put any in it in spring just to run it a bit.Sometimes it will run around field and not miss a beat till i turn blades on.any ideas?Paul

I would take the blade belt off and make sure everything turns easy.

ake the cover off the engine so you can see the entire top of the carb.
The throttle buterfly is the one closest to the engine,
It will have a solid rod attached to it and the other end should be attached to the govenor arm.
These can get stuck and even rust solid is not used for a long while so start the engine and work the rod back & forth.
The engine should rev up and down as you do this.
If it revs up and down the carb is fine & the govenor requires attention.
They havae springs that rust & fall off, get stuck, if it is internal the bob weights can get gumed up and if external can get debris orpund the air vane that stops them working.

When you set the throttle to start that rod should go full open.
As soon as the engine picks up revs it should close down