96 Windstar CEL Codes p0161 & p0174

I had 5 codes a few weeks ago, which did not suprise me since I had a major leak in my cat converter. I had it replaced (entire Y pipe - oem) last week and cleared the codes. Ran a test again when the cel came back on and these two remained. I cleared them again just to be sure and drove another 40 miles and the same 2 came back.
This looks like it is the same O2 sensor for both codes, am I correct? Also I had some codes last summer and did the cleaning the injectors and egr ports, all egr sensor/valve, and DPFE, the whole 9 yards. The O2 sensors were replaced then as well, and I have checked the connections yesterday.
Any idea where I should start? I appreciate any help you can give me!