I've got a 97 EB Expedition 4X4 5.4L with 105,000 miles.
The thing has been sitting in my garage for 3 or 4 months, and initially it would not idle at all (a slow stumbling death). I replaced the IAC valve and that fixed the idle. However, it would stumble badly on acceleration, shift hard, and lack power at cruise. The code read at P1132 (Lack Of HO2S11 Switch - Sensor Indicates Rich). They cleaned the MAF sensor and reset the computer. This took care of most of the problem, but 20 miles later, the CEL came on again. They replaced the MAF sensor. The problem seemed gone until 1 to 2 minutes after running, the CEL came on again this time the code was P1133 (Bank 1 Fuel Control Shifted Lean (FAOSC)). The stumbling was there again, but to a much lesser degree. In cruise, the power drops a little but only for a minute, then is ok for long periods. I think I imagine a stumble when I let off the gas as well. When the engine was cold and before the CEL light came one, it ran great.

Some of the rough running was present before I parked it, but it was not bad, just annoying.

The shop is busy until next week, but I'll be gone. I trust the guy at the shop where I go now and really don't want to go to the dealer, but I will if necessary because I want to take this vehicle on the road.

By the way, plugs were changed recently, 1 cop replaced (#3), PVC line replaced (I had a hole, too), fuel filter changed, air filter replaced.
I've visually checked around the O2 sensors for leaks, corrosion, etc but found none. Checked induction connections for security.

Any suggestions for where to go next? I don't want to start a parts replacement frenzy. Did I supply all the necessary info for the collective brainpower of this group? Thanks in advance.