I have a Craftman 26” front tiller with Briggs &Stratton 5HP I/C engine which has served me well for several years. However it now fails to reach full power. After starting it would conk out when moving from “Choke” back to “Run”. I cleaned the carbureator which is on top of the gas tank including the base of the intake stem and there was an improvement. It would not conk out if set to “Run” but it still will not get to full power. It accelerates OK when throttle is manipulated by hand but will not stay at full power.

Hi,
Did you try a new diaphrgm? It is on the side of the carb behind that rectangular plate held on by four screws. One of the most commonly replaced items. Or try:
Your online source for Replacement Small Engines. Horizontal Shaft Engine Measurements. (http://www.smallenginesuppliers.com/shop/html/horizontal_shaft_measurements.htm)
To see how to go with an Intek. Give model and type and I will look it up for you.
Peace,
Clarke