Welcome! For future reference, it's always best to have the actual code that was read when you have a Check Engine Light (CEL), because we can get right to the point.
From the info you've given, I'd say the first, most likely culprit is the Oxygen Sensor closest to the engine.
Forget the "bank" nomenclature, as your inline 4 cylinder has only one bank. Us V6 guys are the only ones lucky enough to have to deal with that confusion.
You have 2 oxygen sensors. One, closest to the engine, is for control of the air/fuel ratio. This one is important and can lead to the driveability problems you're reporting if it goes bad.
The second one, after the catalytic converter, is an emissions sensor to monitor the cat and alert the driver to one that is going bad. If that sensor goes, you would never notice except for a CEL staring you in the face.
However, without the code I can't say for sure. There could be other things that would cause that problem. Take a ride to any Autozone (or your g/f's brother's store) and get the actual code number. Myself or someone else can copy and paste the exact instructions from the Ford Service Manual. Don't go throwing parts at the problem - that can get very expensive very quickly. We'll take care of you.
