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

[FL 3.2L]

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!!

[Franco2112]

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.

[rhandwor]

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.