This is a new one for me! My 3-year-old Craftsman R1000 starts fine and runs perfectly for about 30 minutes. Then it begins surging and eventually quits altogether. If I choke it before it quits, it will speed up momentarily but then begin surging again as soon as I turn off the choke. After it quits,it will restart in about 10 minutes but then begin surging after just a couple of minutes of running. Loosening or even removing the gas cap makes no difference. I disabled the carb solenoid a couple of years ago. I have replaced the in-line fuel filter and the in-line shutoff valve. It certainly acts like it is starving for fuel when it surges and quits, but why? Any ideas?
