I have seen other threads here in the past with different tractors, but the same intermittent stalling out. Well mine was doing it as well. It's a L3700 SU HST. Has about 300 hours on it as of now. The problem was always unpredictable when it would bog down and eventually stall out. It would always restart and chug a bit before running smooth again. But it was impossible to know when it would bog out. I had done the standard repairs....new fuel filter, make sure there is no slime in the fuel, add 911 additive,new gas cap, replace HDT neutral switch, etc. I explained hat was happening to the mechanic ( not the service writer ) ..and the mechanic immediately said to change the entire fuel filter housing. It's a little plastic inline thing that has a ball valve..and apparently the ball valve has a history of getting clogged up. The part was about 20.00 and took about 5 minutes to change. Yesterday was the first time I had a chance to run the tractor for any length of time and after 2 hrs of grading my road, it ran like a champ. No bogging, never stalled..actually ran better than I remember it running when it was new. Thought I would share my experience with others who are having similar problems.