2001 Exp - running a little rough at idle and on accel

Posting for a friend with a 2001 Expedition with the 5.4L V8 Triton engine. It's been a good vehicle for him and it has 122K. About 10K ago, we did a plug change and coilpack swap to resolve a single cylinder misfire. It ran great until a couple weeks ago when he noticed a rough idle and what felt like a misfire on acceleration. He also noticed a couple mile per gallon decrease in fuel economy. There is no check engine light and I could pull no codes from it, pending or otherwise. There is a little roughness to the idle, but I don't think I'd call it a misfire. I looked at live data provided by my scanner and the only thing that looked out of ordinary to me (I am a shadetree mechanic...at best!) was the value for the post cat sensor on Bank 1. Its value went down when I gave it gas, whereas the value for the post cat sensor on Bank 2 went up. I really don't know if this is significant or not, but it was the only data that stood out to me. Until this truck throws a hard code at me, I'm not going to be able to solve it. We checked for vacuum leaks. We changed the air filter. Any ideas? Thanks!!

Recheck your spark plug and wires. One or more of your spark plugs may have cracked or plug wire is damaged/ worn out if original.

On a 1997 Ford F-150 I had I run across the same problem and I used Winn induction cleaner. I used a can with a small hose and valve I let the vacuum pull the cleaner in and the engine run much better. I also installed new plugs.