Fueling & Injection - Can changing the fuel pump/fuel pressure regulator hurt my mpg?

I got them changed about 7 months ago, and shortly after, I began getting about 6-7mpg and my 02s are fouling out often. I've been running around in circles trying to find the problem and cannot figure it out. Could something with the fuel pump/fuel pressure regulator cause it? The fuel pressure shows 58psi, and lowers a couple psi under acceleration.

ANY HELP IS MUCH APPRECIATED!!

Patrick.