Since Ford's TSB 04-24-22 air intake horn is discontinued, your best options are fabricating a custom shield, relocating the intake, or installing a snorkel system. Several F53 owners have successfully used aftermarket solutions.
V10 surging with air/fuel codes often has cheap fix - vacuum leak, intake gasket, or exhaust leak. Do smoke test or spray test before replacing more expensive parts.
P0420 with surging often indicates exhaust leak affecting O2 readings. You replaced one manifold gasket - check the other side. V10s commonly have issues with both manifolds.
P0171 and P0174 together indicate system-wide lean issue. Most likely intake manifold gasket, PCV system, or MAF sensor. V10 known for PCV elbow and intake gasket issues. Smoke test recommended to find vacuum leaks.
P0171 lean code with no drivability issues is safe to continue driving for your Florida trip. Monitor for symptoms. MAF cleaning was good step - may need replacement if code returns. Check PCV and vacuum lines when convenient.
V10 hesitation often dirty throttle body, weak coil, or fuel pressure. Clean throttle body and MAF first. Check fuel pressure under load.
Your 1988 E350 Class C with 460 EFI has spark, fuel pressure, and timing but won't start even with ether - this points to either a faulty Mass Air Flow sensor, clogged injectors, or ECM failure. The fact that ether doesn't help is the key diagnostic clue here.
Your 2015 Bounder's Ford V10 crate engine symptoms point to incomplete engine installation/tuning issues, not transmission problems. The shop likely hasn't properly completed the crate engine setup.
Your intermittent check engine light on the 1996 F530 460 V8 is likely caused by a failing sensor, loose connection, or intermittent fault that's not staying active long enough to be easily diagnosed. The most common culprits are the oxygen sensors, mass airflow sensor, or corroded wiring connections.
V10 dying in sharp turns often low power steering fluid or dirty IAC valve. Check fluid first. Clean IAC if fluid OK.
Lean on both banks indicates system issue not O2 sensor failure. Check for vacuum leaks, MAF sensor, and fuel pressure. Minor transmission leak in reverse is likely front pump seal weeping - monitor but not critical unless worsens.
Your 2014 Fleetwood Bounder's V10 random misfire at high RPMs on hills is likely caused by fuel delivery issues under load or remaining ignition components that haven't been replaced yet. The intermittent nature and specific conditions point to fuel pump weakness or injector problems.