The 2005 Isuzu 4HL1 smoother E engine has no power over hills what could be th problem

What car, why not say what car?
what country. is it. (name vary by country )
ah Smoother is a transmission on and ELF huge truck, not sold here, in USA on our USA forum.
so...
same, lost compression
fuel delivery
filters clean? all filters related.? (air /fuel)

here is the list, which one?
did you scan the PCM yet? is it a turbo.?

• The 4HL1 is a common rail direct injection OHC 16V high-pressure fuel injection system diesel engine of 4.777 L capacity with electronic control system. Peak torque is 333 Nm, peak power is 140 PS (103 kW) at 3,000 rpm. Maximum torque is (34.0 kg m)'/1,500 rpm. Bore is 115 mm, stroke is 115 mm.
• The 4HL1-N is a common rail direct injection OHC 16V high-pressure fuel injection system diesel engine of 4.777 L capacity with electronic control system. Peak torque is 333 Nm, peak power is 131 PS (96 kW) at 3,000 rpm. Maximum Torque is (34.0 kg m)'/1,500 rpm. Bore is 115 mm, stroke is 115 mm.
• The 4HL1-TC is a common rail direct injection OHC 16 V turbocharged and intercooled high-pressure fuel injection system engine of 4.777 L capacity with electronic control system. Peak torque is 425 Nm, peak power is 160 PS (118 kW) at 2,700 rpm. Maximum torque is (43.3 kg m)'/1,500 rpm. Bore is 115 mm, stroke is 115 mm.
• The 4HL1-TCS is a common rail direct injection OHC 16 V turbocharged and intercooled high-pressure fuel injection system diesel engine of 4.777 L capacity with electronic control system. Peak torque is 500 Nm, peak power is 179 PS (132 kW) at 2,700 rpm. Maximum torque is (51.0 kg m)'/1,500 rpm. Bore is 115 mm, stroke is 115 mm.

Loosing compression
fuel delivery

if its the DiD ...internal carbon build up