2006 Ford Fusion P0451 Code: Post-Collision Intake Manifold Repair Causes Poor Acceleration and Air Leak Symptoms

Hi, I have a 2006 Ford Fusion 2.3L automatic with a history of collision damage. During the accident, the intake manifold was broken. We replaced it and reassembled the unit. Since then, the vehicle has been displaying Diagnostic Trouble Code P0451 — indicating an issue with the evaporative emission control system pressure sensor or circuit. The car struggles to accelerate, especially when starting from a stop, and exhibits a loud whistling or hissing sound that sounds like it's drawing in excessive air. It runs smoothly once it reaches cruising speed. I'm wondering if this is related to improper sealing of the intake manifold after repair, or if there could be an underlying issue with the evaporative system. Any suggestions on how to diagnose or fix this P0451 code? Thank you for your help.