cause of lean fuel, car hesitates on acceleration

Hello,

There are a number of reasons why it will have a lean fuel mixture.
It could be due to a vacuum leak, exhaust leak, dirty mass air flow sensor, faulty oxygen sensor.

The best course of action would be to take a look at each individual item and take appropriate action.
Check for vacuum leak under the hood, look for any cracked hoses. You can also use a carburetor cleaner to check for vacuum leak on the intake manifold. Simply start the vehicle and let it idle. Then spray the carb cleaner on the base of the intake manifold, if there is a leak the engine will react to the chemical and will idle high and go back down after it burns off.

Dirty mass air flow sensor will also cause lean fuel mixture. Cleaning out the mass airflow sensor can improve the air fuel ratio.

Take a look at this helpful guide, it covers all the basics:

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Let me know what you find.
Thank you.