How do i fax that airflow sensor out ofoperating range

OBD code 121 is usually a TPS.
Take a look at this site.
P0121 Throttle Position Sensor Switch Circuit Range Performance Problemvar...

The computer logs this code when the mass airflow sensor indicates more airflow than expected. Is the engine idling high? It could be that the idle air control valve is jammed open. Or, there could be another excessive air flow path downstream of the airflow sensor. Check all hoses connected to the inlet duct between the airflow sensor and the throttle body. Are any of them connected to the intake manifold?

You have a vacuum leak somewhere, leaning out the system. Most of the time it can be traced down to either one of two things. 1.) Check your EGR valve (clean/check wires/check hose connections/ect) or 2.) you have leaking intake gaskets. The way your describing the symptoms, my two cents would be on that EGR Valve. Good luck, hope that gives you some direction!

Sounds like a dirty air filter is putting the mass airflow sensor out of range. The throttle position sensor is subject to physical wear, the age of your truck warrants replacing it. The coolant temp sensor controls the Idle Air Solenoid which determines idle speed ( cold, high idle, 1200 rpms open loop mode for the ECU) and (hot, low idle, 800 rpms, closed loop mode for the ECU) If the truck does not have a Mass airflow sensor, check the Manifold absolute pressure sensor (MAP). Perform an OBDII scan for stored fault history to avoid buying parts you don't need. Do the cheapest fixes first. Go ahead and change the fuel filter also. There is a lot of water in todays fuels

P0101 Mass Air Flow, P0300 random misfire, Your problem is the Mass air flow, the P300 is the result of the mass air flow range, Mass air flow is a hot wire sensor they fail when contaiminated, as for the P300 that the engine detecting the condition when the mass airflow range is out, but here is another problem 1998 Buick used a back up its called a map sensor its on the top of intake plenum, make sure its seated and wire connection are there, Now you are going to fix the problem yourself if you ever taken out ,a airfilter and replaced it, then all you need to do is purchase a MAF cleaner mass airflow cleaner or brake cleaner or electrical cleaner clean the inside of your mass airflow you dont have to replace it the code is range performance the hot wire cant clean itself, so someone has to do it

it is most likely the throttle position sensor. it could be mass airflow sensor. are there any codes? best bet get it scoped and see which sensors out of range.

2 airflow sensor out of operating range 3 coolant temp sensor out of operating range 4 oxy sensor indicates full rich 5 throttle potentiometer/airflow sensor... (low throttle pot signal with high airflow sensor signal) 6 throttle pot/airflow sensor...... (high throttle pot signal with low airflow sensor signal) 7 throttle pot...idle fuel adjustment failure(idle speed??) 8 intake air temp sensor...open or shorted circuit to sensor 11 Throttle pot at idle: Throttle pot idle trim out of normal range 12 Airflow meter: MAF signal out of range 14 Coolant thermistor: Resistance out of range or static during engine warm up 16 Air thermistor: Resistance out of range 17 Throttle pot: Out of range 18 Throttle pot/Airflow: Low throttle pot signal at high airflow 19 Throttle pot/Airflow: High throttle pot signal at low airflow 22 Fuel pump drive: ECU output to fuel pump relay 23 Fuel supply: Engine running too rich 24 Ignition Drive: ECU output to ignition Amp 26 Air leak: Engine running too lean 29 ECU self check 33 Injector Drive: ECU output to injectors 34 Injector: Looks for Injector dribble 37 EGR Drive: ECU output to EGR switching valve 39 EGR check sensor: EGR not working (normally pipe blocked) 44 Lambda (O2) sensor: Poor mixture control rich or weak (or misfire) 46 Idle speed Control valve: ECU output to Coil AB 47 Idle speed Control valve: ECU output to Coil CD 48 Idle Speed Control Valve: Stepper motor grossly out of position 66 Air pump: ECU output to air pump relay 68 Road speed sensor: Seen speed < 5km/h at high engine airflow 69 Drive/Neutral switch: Seen cranking in "D" or high airflow in "N" 89 Purge Valve drive: ECU output to purge valve
this is all I could find

This sounds like a normal condition.What happens is the cold start emission reduction component monitor(software program in the computer) is running.
Cold Start Emission Reduction Component Monitor
The Cold Start Emission Reduction Component Monitor was introduced for the 2006 MY on vehicles that meet the
LEV-II emission standards. The monitor works by validating the operation of the components of the system
required to achieve the cold start emission reduction strategy, namely retarded spark timing and elevated idle
airflow.
When the CSER strategy is enabled, the idle air control system will request a higher idle rpm, elevating engine
airflow. While this CSER elevated airflow is requested, the low airflow test compares the measured idle airflow from
the MAF sensor to the commanded idle airflow from the idle air control strategy.

Have you tried replacing the Throttle Position Sensor? It's more than likely that the TPS is faulty than the air flow meter. The TPS has small strips that ride under a claw, which is where the sensor gets its signal. Give that a try.

Have you checked the power and ground supply to the MAF. They are right the barometric pressure sensor and the intake air temp sensor are built in to the MAF.