I finally got my NAA back together and half ways running good. I put new plugs, wires, points, cap and rotor. I also rebuilt the carb. OK so when im running between 1200 and 1600 it starts to drop then rev up drop and rev up and so on. I adjusted the power needle on the carb, srcrewed all the way in the out 1 turn. Same thing with the idle screw. When im running it at 1800-2100 it runs fine, no surging. I checked the distributor timing at 8 degrees and it was pointing right at number one. I hooked up my timing light took the tractor to 2100 and 8 degree line was perfect with the arrow. Anybody else had this problem or no of a solution? Thank you!