shingles

Ever since I changed my header to ITR on an otherwise stock GSR, I've been getting check engine code. It's a 45 (Fuel system too rich or lean). 0172(too rich) when pulled with an ODBII reader. According to service manual, this could be a ton of things... one of which is the valve clearance(if it's too tight). this made sense so I adjusted the valve but the light still comes on...

one thing that it said was O2 could be bad... but, everything was peachy before I swapped... I mean wtheck!.

Any other suggestions or ideas?

I'd hate to spend $200+ on an O2 if there's no problems....

thanks
-s