1835b running weird at part throttle

I believe I’ve posted on here about my 1835b before. 13000-ish hours, was formerly plugging up the return line and it was advised I rebuild the pump. So I did. Rebuilt the pump, rebuilt injectors (had to replace 1 as that one couldn’t be rebuilt), new intake and valve cover gaskets…and now it’s running oddly. Prior to this work, it started and ran fine until the return plugged up, then it wouldn’t run at all. Now, it starts hard. This loader has always been a little cold blooded, but now cranks a while no matter if it’s warmed up or not. Always smokes like an absolute chimney for at least 30 seconds after starting (again no difference whether cold or hot start), and during those 30 seconds it won’t rev. Just sputters and misses, then it acts like it clears out, stops smoking and runs pretty normally. At this point, at 3/4-full throttle, it runs like a top. Doesn’t smoke, feels a bit more energetic than prior to the rebuild. All good. And it seems to idle well too. However, right off idle til a little past half throttle, it starts smoking again and feels like it’s breaking up a little bit. Smoke is white, maybe a little bluish but definitely not black.