P0340 OBD2 Code on 1997 Jeep Grand Cherokee ZJ 4.0L 4x4: Causes, Diagnosis & Fixes

I recently pulled an OBDII diagnostic code P0340 on my 1997 Jeep Grand Cherokee ZJ with a 4.0L V6 engine and 4x4 drivetrain. This code indicates a circuit issue with the Camshaft Position Sensor (CMP). The vehicle requires two attempts to start, and the engine only starts reliably after multiple tries. I've already replaced several components including transmission sensors, gas cap, thermostat, front and rear transmission seals, and leaking gaskets. No other diagnostic trouble codes have appeared, and the engine runs smoothly under normal conditions—except when attempting to start it from a cold or hot state. The issue only manifests during rapid cranking attempts, where I hear gear meshing noises. This suggests mechanical stress may be influencing sensor performance. I've used an injector cleaner and replaced spark plugs and wires less than 30,000 miles ago, so fuel system issues are unlikely. The vehicle was garage-kept in Southern California for over a decade and has accumulated 150,000 miles since new. Prior emissions codes (P0720 and P0740) were resolved after transmission work. All gauges and cruise control function properly. The only non-operational feature is the Anti-Lock Braking System (ABS), which requires a new computer board or brake sensors—this is unrelated to the current issue. I'm concerned about whether the Camshaft Position Sensor is truly the root cause, especially given that some sources suggest failure of this sensor can lead to increased starting difficulty. I've read that if the sensor is not properly installed or connected, engine cranking issues may worsen. Should I investigate other possibilities such as fuel pump failure? While the fuel pump location makes it a potential concern, my mechanic has ruled it out based on current symptoms and the presence of P0340. However, I'd like to confirm whether there are any overlooked factors that could trigger this code. Any guidance or troubleshooting steps would be greatly appreciated—especially regarding how to properly diagnose the CMP sensor using a multimeter or fuel pressure gauge.