I have been having the same issue with mine, no power untill 2,500 rpm, which unfortunately is the point where it upshifts, so it also causes uncomfortable jerking when it shifts. I have adjusted my ALDA 4 times, one rotation each time. It will work fine for a couple of days, but then slowly gets worse until I unscrew it another turn. How much can you turn that screw before it can no longer be adjusted?

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head