2002 chevy blazer codes 443 449 i replaced the maf sensor the vaf sensor on air horn the emmision valve on the engine the vent valve to even tried the gas cap clear codes drove the truck guess what codes are back 443 449 what do you think

A MAF=Mass Airflow Sensor. VAF=Vane airflow sensor
A MAF measures quantity and density of air coming into the engine. If you unplug the MAF and try starting, the computer will default to factory programming and will calculate air and fuel based on outside air temp, engine temp and pedal position.

code p 101 refers to mass air flow(MAF)sensor/volume air flow(VAF) sensor --range performance problem====causes --intake leak/blockage---MAF/VAF sensor

code p 0171 refers to system to lean bank 1===causes ---intake /exhaust leak---AIR system---MAF/VAF sensor ---fuel pressure/pump---injector/s---HO2S ( heated oxygen sensor --the one in the exhaust manifold before the cat converter bank 1)

I don't have a listing for the c code but from the other 2 codes I would be checking around the maf/vaf sensors and the HO2S sensor (replace)
start with checking the wiring and connections to both units

code p 0102 refers to mass air flow(MAF) sensor /volume air flow (VAF) sensor --low input===causes --wiring short to ground ---MAF/VAF sensor ---ECM
check wiring for insulation problems or broken connections
replace the MAF sensor

code p 102 refers to mas air flow (MAF) sensor/ volume (VAF) sensor ---low input===causes --wiring short to ground --MAF/VAF sensor ---ECM
code p 103 refers to MAF/VAF sensor ---high input====causes --wiring short to positive ---MAF/VAF sensor---ECM

code p0102 refers to mass air flow (MAF) / volume air flow(VAF sensor-- low input===causes --wiring short to ground---MAF/VAF sensors---ECM
I would replace the MAFor VAF sensor after having each one tested to find the faulty unit.

code p0101 refers to MAF sensor and VAF sensor--range /performance problems===causes --intake leakage/blockage ---MAF/VAF sensor failure.

code p0300 refers to random misfires multiple cylinders ---causes --spark plugs /HT leads --injector /s-- ignition coil/ s--low compression ---wiring

check fuel pressure in manifold and HT leads

code p0171 refers to system too lean bank 1 ===causes --intake /exhaust air leak---AIR system---MAF/VAF sensors ---fuel pressure /pump---injectors ---HO2S sensor

Basically there are two codes referring to the MAF/VAF sensors so check them out and two codes referring to fuel pressure and pump so have a pressure test done on the fuel manifold to determine if pump or pressure regulator.

code p0102 refers to mass air flow(MAF) sensor/ volume air flow(VAF) sensor --low input===causes--wiring short to ground--MAF/VAF sensor/s--ECM

clean or replace the MAF/VAF senspr

code p0102 refers to mass air flow(MAF) sensor/ volume (VAF)sensor --low input==== causes --wiring short to ground---MAF/VAF sensor---ECM
replace the MAF or VAF sensor.

code p0102 refers to mass air flow (MAF) sensor/volume air flow (VAF)sensor --low input===causes-- wiring short to ground---MAF/VAF sensor---ECM
replace sensor

P0101 is the Mass Air Flow Sensor error,
http://www.obd-codes.com/p0101


P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature