07 DR-Z400S 4000 miles Stock carb with 2" end cap/ no spark arrestor Stock engine Stock carb 150 main 25 pilot with stock fuel screw DJ needle on 4th clip Fuel screw 2.75 turns out 3x3 mod No Toil Pre Oiled air filter. Most riding between 1500 and 4500 ft. elevation Temp(40 - 80) The problem i am having is low rpm bog once I get to about 2000 ft. elevation. I live at a thousand and have jetted per recomendations. I feel like it is not getting enough air. It always seems to happen at the time you really need it to blast out of a creek or corner. I am wondering if: A. The main jet is too high and I should go back to 142.5 stock main B. The fuel screw needs to be turned in to lean things out. C. Go to the 142.5 main and set fuel screw to 2.5 turns These are my uneducated guesses at what I should do. If you could help me that would be awesome. Thanks for the help!