As I ride my Sabre 2048 tractor with it's 35VOHV2 Intertek engine there is a periodic rumble that sounds perhaps like the engine is choking. Whether the blades are engaged or not the tractor "rumbles", slightly hesitates briefly and then goes on just fine. This occurs with no regularity but in the space of 20 minutes it might occur 10 times. The sound is the same sound the engine makes if the seat is lifted and the engine is automatically shutting down. Again, it is like the choke has been left on(?), but I check to make sure it is all the way down. I'd like to perhaps fix it myself if I can. The gas is fresh the oil and air filters are new and or clean. The inline gas filter is only about three months old.