Almost a year ago I was fighting an issue with a poor running 1650 gas. Then it would spit, sputter, and die. Leave it off for 10 minutes and it ran normal. Well I started diagnosing things and the issue pointed toward a carburetor problem. In this time it was due for a tune up. Plugs, wires. It has electronic ignition. Also took the gas tank off and had it cleaned at a radiator shop. Still ran poorly so we ended putting on a remanufactured carburetor. With some minor adjusting the tractor ran great and we used it as the rake and tedder tractor all haying season. I should now mention our land has some rolling hills but not necessarily steep grades. Today we brought the haying equipment back from my brothers property to the farm. There are several long fairly steep grades. Tractor ran fine till part way up first hill. Started spitting and sputtering again. My brother had to downshift to 3rd gear to make it up the hill. Second hill it did the same, stalled out a few times and he was all the way down in 1st gear to make it up. Tractor should pull that hill in 6th direct. The only thing I can think of is maybe the float height is way off causing fuel starvation ? Only happens going up long grades. Gas tank was 3/4 full. Any thoughts ?