2007 Ford Navigator P0340 and P0344 Fault Codes: Diagnosis and Repair Guide

My 2007 Ford Navigator is running smoothly with no starting issues, excellent mileage (185,000 kilometers), and consistent engine performance. However, I've been encountering Diagnostic Trouble Codes P0340 and P0344 related to the camshaft position sensor. Key observations: - The vehicle runs perfectly under normal conditions—no rough idling, no stalling, no power loss. - When the ignition is turned on (engine not running), I used an OBD2 scanner to clear both P0340 and P0344 codes. After starting the engine, the code occasionally returns—but not every time. - I took the vehicle to a Ford dealership, where they recommended replacing the camshaft position sensors, VVT solenoids, and even the PCM (Powertrain Control Module). Despite this, the check engine light remains on. - The issue appears to be triggered only during startup—once the engine is running, the code does not appear. This suggests it may be a startup-related fault rather than an ongoing operational problem. - I am skeptical about the dealership's diagnosis, as they charged thousands of dollars for a solution that doesn't resolve the root cause. My question: Since the code only appears during startup and disappears when driving, what could be causing this intermittent behavior? Is it possible that the issue lies in wiring or sensor signal circuits rather than hardware failure? Note: The vehicle has 185,000 kilometers (approximately 114,700 miles) of mileage—this is a high-mileage vehicle with no visible mechanical issues. Thanks for any insights or technical guidance on diagnosing P0340 and P0344 in the 2007 Ford Navigator.