Ever thought it might be the clutch is wearing out?
symptoms fine on flat and downhill no power up hill.
Test 2nd gear hand brake on try pulling away if it stalls may not be clutch if it revs it's most likely the clutch.
Black smoke seems strange considering new injectors. Who do the gasket? has the head been tightened to proper Torque ie tighten properly and in correct sequence?
Bob
September 2010