The bucking sounded like an ignition miss or lean condition. It seems it only recently is giving you lean codes from your exhaust sensors though. Fuel filter could be plugging up. I don't know if driving around with a fuel pressure gauge hooked up will tell if it's a pump or the filter. You had the idea first.
I don't see where you have adjusted the TPS. It works with the IAC and I assume its closely involved with timing advance under partial throttle where you are bucking. With a multi-meter its free to check and adjust to correct voltage. There's good threads around here explaining how to do it.
I'd also verify your throttle body is closing the butterfly completely and is clean and moves freely.
1992 Tbird LX 5.0, 3.73 gears, 1995 Cobra intake, deleted air silencer, 2.5" mandrel bent dual exhaust, SCP shorty headers. Updated four-hole fuel injectors. SK shift kit in AOD. Vogtland 0.9" springs, Tokico and Bilstein shocks.