code p0172, o2 sensor didn't help

I'm getting a check engine light on my 96 Grand Am. The code is p0172, mixture excessively rich bank 1. I changed the o2 sensor, and this helped a little at first, but not for very long.

The engine bogs bad if I give it a little gas, sometimes stalls. (A real pain at rush hour) It has no trouble with a a moderate amount of gas.

I have started to smell a little bit of gas in the cabin.

Can anyone help me??!!??!!

A P0172 is a rich mixture indication that the O2 sensor cannot compensate for.
Without knowing what size engine is in your car, I would check to see if you had a fuel pressure regulator leaking into the vacum port.
With the engine off, pull the vacum line off the regulator and look to see if there is any moisture (raw fuel) in the vacum line.

it's a 1996 2.4L quad-4.

Thanks, I'll check that out. Wish me luck!