When first start my husqvarna yth 150 runs fine goes up hills plenty of power after running for while starts loosing power wont go up hills will stll move on flat surface

sounds like the bearings on one of the pulleys are grinding, remove the deck and do a closer inspection.

Check all electrical connections and check diodes in charging circuit.

Hydro gear box takes a sae 20w 50 motor oil, Tuff Torq takes a sae 10w 30 motor oil

is it loosing spark when it dies?like the coil is bad or there's a nest under the cover and the coil is overheating

is the vent in the fuel cap plugged?is it loosing spark?

that just leaves the battery, the terminals, or the wiring.

i would say you have a blockage in the fuel system. possible dirty carburetor. check carb bowl if you see any dirt or water. take off and clean. be sure fuel lines and filter are good. check air filter also.

If I understand, you were mowing and it just stopped running. The motor didn't sieze up, it turns over. Okay and you have spark, and you have gas, have you checked the safety switches. there is one under the seat, the blades, the brake pedal when starting. Make sure that these safety switches are working properly. that is the next step I would take.

you have a safty switch bad on mower for the clutch make sure you have 12 volts golng to it.ok let me know