I have been having some issues with my car throwing P0131 and P0171 codes. Occasionally, when I am driving the car at 40 or 50 mph it feels like its stuttering and is jerky (I expected for it to be misfiring but when I scanned the codes there were no misfire codes. I just replaced the O2 sensors a month or so ago and the fuel filter a couple of years ago. Car has long tube headers.
Whenever I take my foot off the gas pedal I hear a metallic squeak coming from the front of the car. The alternator and tensioner were replaced a little over a year ago and the belt was replaced with a gatorback belt several months ago. Any ideas to resolve any of these issues would be appreciated. The car also has been throwing a P1637 code basically since the alternator got replaced.

 

Have you checked for vacuum leaks? That's the first thing I do when I get a lean code such as 171. Looks like you have a LS6 intake there by your sig pic, I would check around the base of the intake manifold with either some kind of smoke or throttle body cleaner.

 

Intake is an LS6, I've had it for several years now, couldn't imagine it developing a leak

 

Could the car be misfiring and just not thorwing the code?

 

The squeaking sound is only noticeable when in the car, not from the front of the vehicle or under the hood

 

And now the car threw a P1810