Periodic CEL and Oxy sensor codes after REPLACING both sensors

[swenpro]

When I had my transmission replaced in December, I also had the mechanic throw on two new oxygen sensors that I supplied. Assuming that he installed them correctly, what could be causing the computer to still throw oxygen sensor #1 and 2 codes??

The check engine light illuminates for a few hours about once a week now too. Any thoughts on this? Thanks in advance

[winfred]

probably has the usual intake leaks and or bad pcv plate, common v8 problem should come up with all the info you need with a search using the words intake leak and or pcv plate

[Tiger]

MAF too.