1998 Ford Explorer idlling

If the check engine light is on, have the computer scanned for trouble codes. Most parts stores will do it for free. If there is no light, check for vacuum leaks, check the idle air control solenoid (IAC) which is located on the throttle body, and make sure there is proper fuel pump pressure. For directions, refer to our homepage under the DIY section for both a video and directions on the fuel pump. You will need a fuel pressure gauge. Many parts stores will lend you one.