Ford: Ford Ranger 2003, vacuum leaks, oxygen sensor

Question
Recently my engine has been surging and missing at different speeds. It races to 3000 RPM's when only @ 40mph. What could be the potential causes?

Answer
If your engine is reving to 3000 while driving a steady 40MPH, then you clutch or transmission is slipping badly. Surging and misfiring can be a large number of things. Does the Check engine light work? and is it on while driving? have someone scan the truck and let me know what they find. Codes can help determine the cause. Vacuum leaks, the state of the tune-up, fuel delivery problems, wiring issues, charging problems , oxygen sensor or other sensor problems or computor problems can all add to, or cause the symptoms you are describing.

If the engine idles ok and the check engine light is not on, I would start checking the plugs and wires, the perform a fuel pressure and delivery test.