If what you have is a MOWER (as in lawnmower) it sounds like it idles and runs but when you engage a load it dies.... This is usually caused by something caught preventing the blade from turning or if it has powered wheels something wrapped around the axel.
NEVER WORK ON A RUNNING MOWER, fingers are a hassle to reattach.
(I remove the spark plugs to insure no compression kicks or ignition)
Clean your mower thoroughly, look for string or debris blocking the free movement of the blade and or wheels.