I suggest you quit with the stupid ideas. You think the factory put too small of an injector in your motor?!! That's a frickin joke. How about having a mechanic fix it the right way? They would start with reading the engine data to see what the fuel trims are at. There are any number of things that can cause hesitation!

Try three things that are DIY fixes. First change your fuel filter if it hasn't been done recently. Then get a spray can of carb cleaner, use that to clean both the IAC and the throttle body while its accessible.

Check your air/idle module near the throttle body. Go to youtube and there may be a video with step by step on how to check ,clean or replace the unit

Change your air filter and clean the mass airflow sensor.

When giving my 2000 Buick Century a bit of gas, sometimes the engine lags before it actually starts to put down power. It dies for a second and them kicks in all at once. I was wondering if this was a problem caused by not having big enough fuel injectors and why it does that. Its annoying and it could be an issue if i ever needed to accelerate quickly to avoid another car or something. Any suggestions would be appreciated. Thanks!