I didnt notice a stumble. I looked through the data from the last 3 runs and with the 2bbl, 4bbl(4160), and 4bbl(4150) and in that 1700 rpm area the air fuel was lean, about 16.6:1 while I was rolling into the throttle and applying the load. It probably had to do with slowly opening the throttle which makes the accelerator pump less effective, but its probably more to do with the power valve not being opened yet. After 2000 rpm or so the air fuel came back down. Hope that helps.