Had that happen to my '96 2 weeks ago. It's the Water In Fuel Sensor (WIF) costs about $50 at the dealer. You can temporarily fix it by removing the sensor and unplugging the wire, wrapping an 1/8" NPT pipe plug with teflon tape and install it into the hole. The WIF light on the dash won't come on if you actually have water in the fuel because, durrrrrr, there's no sensor. Leave it with the plug in it, or shell out the $50 and replace it.
The Ford part number I have for the WIF Sensor is: E8TZ9J308A