If it upshifts good but downshifts poorly, either your synchros are worn or you need to change the type/weight of oil. On an upshift, the engine slows to meet the transmission speed. On a downshift, the synchro has to spin up the clutch disc to meet the gear speed which is a lot more work, and it sounds like you're caught between the two. I'd suggest draining your oil (keep it for something else, like the rear end) and adding plain ol' 75w90 GL4 dinosaur poop. That will tell the condition of your synchros. Blipping the throttle of course lessens the load on the synchro and shortens wait time.