* Fuel System Issues: Even with good oil pressure, the engine needs fuel. Check the following:
* Fuel Pump: While you mention 55 PSI *oil* pressure, the fuel pump pressure needs to be checked. Low fuel pressure, a clogged fuel filter, or a failing fuel pump relay are common causes of engine death.
* Fuel Injectors: Clogged or faulty fuel injectors can prevent fuel from reaching the cylinders. A fuel pressure test should also assess injector function.
* Fuel Delivery Lines: Check for leaks, cracks, or kinks in the fuel lines from the tank to the engine.
* Ignition System Problems (despite new parts):
* Distributor Cap and Rotor: Although you replaced the pickup coil and crank sensor, the distributor cap and rotor can still cause intermittent misfires and stalling. Inspect for cracks, corrosion, or worn contacts.
* Worn Spark Plugs or Wires: Even if they seem okay, worn spark plugs or wires can lead to inconsistent ignition. Replace them.
* Ignition Module (or Coil Pack if it has one): A failing ignition module (or coil pack) can cause the engine to die unexpectedly. This needs testing.
* Wiring Harness: Look for any damaged or corroded wires in the ignition system, especially near the distributor.
* Computer/PCM Problems:
* PCM (Powertrain Control Module) Failure: The PCM controls many aspects of the engine. A failing PCM can cause unpredictable engine behavior, including stalling. This requires diagnostic scanning with a professional-grade OBD-II scanner. A simple code reader might not be sufficient.
* Sensor Issues (beyond what you've replaced): Other sensors, such as the coolant temperature sensor, mass airflow sensor (MAF), or oxygen sensors can affect engine operation and cause stalling.
* Vacuum Leaks: A significant vacuum leak in the intake manifold or vacuum lines can starve the engine of air, leading to stalling.
Troubleshooting Steps:
1. Fuel Pressure Test: This is the most crucial step. Measure fuel pressure at the fuel rail with a gauge to ensure it's within specifications.
2. Visual Inspection: Carefully examine all wiring, fuel lines, vacuum lines, and components for any signs of damage, corrosion, or leaks.
3. OBD-II Scan: Use a professional-grade scan tool to check for any diagnostic trouble codes (DTCs) stored in the PCM. This will provide valuable clues.
4. Spark Test: Check for spark at each spark plug to rule out ignition problems.
5. Vacuum Test: Use a vacuum gauge to check for vacuum leaks.
It's highly recommended to take your van to a qualified mechanic for diagnosis and repair. The problem could involve a combination of factors, and a professional has the tools and expertise to pinpoint the cause accurately. Continuing to drive the vehicle with intermittent stalling could cause further damage.
