O2 Sensor

[84LX89GT]

How is the idle? if you spray some brake clean, carb cleaner or propane around the intake at idle and the engine runs better or revvs there's likely a vacuum leak around where you sprayed that would cause that code. Bank 2 if i remember correctly is the driver's side, so check for any holes in vacuum lines, especially PCV lines running from the valve cover to intake manifold. If the fault occurs at cruise speeds you might be looking at plugged injectors, fouled plugs maybe even a blown head gasket if it causes a misfire. Check compression, what the plugs look like, fuel pressure, and check for vacuum leaks and hopefully that will narrow it down.
Good luck.