Hey, newbie here with a couple of questions for you guys who are in the "know". I recently bought a used (2004) ExMark Turf Tracer 60. (Kohler Command 20) I got it to replace an older 72 Scag walk behind I sold to the folks who bought my house. Heres the deal, this mower runs great sitting still. It will idle and rev up just fine, put a load on it (up hill, thick grass, quick manuever, etc.) and she dogs out. It smokes and sputters till I throttle it down. I can cut at about 3 or 4 (speed wise) and about 5/8 throttle, any higher than that or through normal height grass and it trys to die on me. ?? Heres what I have already done to it that has has ZERO effect on how it runs so far. 1) New fuel and fuel filter. 2) Changed oil, oil filter, trans filter trans fluid. 3) New plugs (which are now badly carbon foulded for some reason?) 4) New float, needle valve, air/fuel screw & gaskets. 5) had the carb apart a total of three times, sprayed it out with carb cleaner & compressed air. Aitr filter looks fine, it runs the same with it off. PLEASE HELP! I'm one step away from taking this thing to an ExMark dealer. It's starting to hurt my pride now. Any suggestions would be great, I'm lsot at this point.