98 grand marquis 3 dtcs please help!!
 

Hey guys I have a 1998 mercury grand marquis and it's running less than perfect. I'm showing three DTC's, they are as follows:
P1151-lack of Ho2s21 switches sensor indicates lean
P0133-o2 circuit slow response
P0156-o2 circuit b2s2

I replaced both cat converters and all four o2 sensors around 3 month ago using quality parts. And I just recently did a tune up...spark plugs, air filter, fuel filter, oil change... I'm noticing a lack of power on inclines as well as a rough idle.. I'm assuming that these conditions can be caused by the lean condition. I'm trying to see if anyone has dealt with a similar problem before I start tearing into anything. I haven't checked the MAF as of yet as I know this is a possibility. Any help or advice is greatly appreciated. Thanks guys.

Thanks for all the advice.. Very helpful..