* Transmission Problems: Jerking is a classic symptom of transmission issues. This could include low transmission fluid, worn clutch packs, a failing torque converter, or problems with the valve body. A transmission specialist should inspect it.
* Spark Plugs and Wires: Worn, fouled, or damaged spark plugs and ignition wires can cause misfires, leading to jerking. Check their condition and replace them if necessary.
* Distributor (if equipped): Older Rangers may have distributors. Worn components inside the distributor, such as the cap, rotor, or pickup coil, can cause erratic ignition timing and jerking.
* Fuel System Issues: A clogged fuel filter, a malfunctioning fuel pump, or low fuel pressure can cause inconsistent fuel delivery, leading to jerking.
* Vacuum Leaks: Vacuum leaks in the intake system can disrupt the air/fuel mixture, causing erratic engine performance and jerking. Inspect all vacuum lines for cracks or disconnections.
* Computer (PCM/ECM): While less likely after replacing the MAF and TPS, a failing PCM or ECM could still be the culprit. This is usually a more involved diagnosis and often requires specialized tools.
* Oxygen Sensor: A faulty oxygen sensor can provide inaccurate information to the computer, resulting in a poor air/fuel mixture and jerking.
* Catalytic Converter: A clogged catalytic converter can restrict exhaust flow, leading to rough running and jerking.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner (though a 1994 might not be fully OBD-II compliant, it might still provide some codes) to see if the vehicle is storing any fault codes. These codes can pinpoint the problem area.
2. Inspect all the basics: Check all hoses, connections, and belts. Look for obvious signs of damage or wear.
3. Professional Diagnosis: Since you've already replaced common components, it's highly recommended to take your Ranger to a qualified mechanic specializing in older vehicles. They have the tools and experience to diagnose more complex issues. A proper scan tool capable of reading the older Ford systems will be necessary.
Don't continue driving the Ranger extensively with this problem, as it could lead to further damage. The sooner you get a professional diagnosis, the better.
