Hyundai Repair: 2001 hyundai santa fe, hyundai santa fe, air flow sensor

Question
my 2001 Hyundai Santa Fe four cyl. it has troubles starting it starts cutting out like its losing power and it makes a rattling noise when i'm going up a hill and the codes that are coming up are po171 and po301 i checked the coils they are fine.

Answer
My first recommendation is to check your fuel pressure.  Low fuel pressure will cause a lean code (P0171) because the injectors must be held open longer than expected to deliver the proper amount of fuel.  It can also cause a misfire due to insufficient fuel.  Typically, the farther the accelerator is depressed when there is insufficient fuel pressure, the worse the engine will run.

Other things you might check:
Intake manifold gasket for leakage (especially around cylinder #1)
Air flow sensor
Fuel injector (especially cylinder #1)