I have a Gt52xls with a stalling issue. It would run fine for 20 minutes the surge and stall. My tractor has a reserve tank valve under the seat. When I took the valve ioff I found the line was almost completely clogged leading to the engine. The reserve tank all ok. I found out Husqvarna no longer puts a reserve tank on new stock. I’m guessing they tend to clog making the 90 deg into the valve.