A high idle speed can be caused by a poor connection at the Throttle Position Sensor (TPS). Connector replacement kits are available from Mazda dealers and possibly some Ford dealers.
2000 Mazda B2500 Problem Reports
Most Reported 2000 Mazda B2500 Problem Reports
Rough Running Idle, Erratic Speedometer Operation, ABS Light Illuminated, Check Engine Light, and Automatic Transmission Shifting Problems
Water intrusion into a connector (X309) located under the cab, beneath the driver's seat, can cause a rough idle, erratic speedometer operation, ABS Light and Check Engine Light illumination, and automatic transmission shifting problems. If needed, connector repair parts are available from Mazda dealers, and possibly some Ford dealers.
The engine may fail to start due to an electrically shorted sensor. Some of the sensors may internally short and not blow any fuses. A technician may find no spark and no operation of the fuel injectors in the diagnosis. One way a technician may isolate the defective sensor is by disconnecting sensors one by one to see if the engine starts.
A dirty, or contaminated mass airflow (MAF) sensor can cause the engine to run poorly. There may be a Check Engine Light with trouble codes relating to the MAF sensor. In some cases, carefully cleaning the sensor element will fix the problem, but replacement may be required.