Small engine carburetor assembly. If the engine runs rough, then the carburetor may be restricted and unable to supply enough fuel and air mixture to the engine.
Carburetor to Gas Tank, 3-5 HP Horizontal (Pulsa Jet)
Carburetor to Cylinder, 3.5 & 5.5 HP Horizontal, 94200 Series (Including 136200 Series)
Fuel tank kit
Briggs & Stratton Fuel Tank. If the fuel tank is leaking or rusty, replace it.