2001 Ford Ranger EGR and DPFE - Computer Fault Codes

On my 2001, 3.0L, 6cyl Ranger Pickup; I started getting the "Check Engine" light at the 52,000 mile oil change. The Garage reset the light and told me that it was probably the DPFE Sensor even though the Fault Code was for EGR Flow. I changed the sensor when the light came back on the following week. The light stayed out for about 3,000 miles and came back on again. Fault Code again was EGR Flow. I changed the EGR Valve, the light came back on within 20 miles. I've re-set it twice since, but it never stays out more than a day or two. Short of pulling the damn bulb... any ideas? Truck seems to miss-fire occasionally when coasting down hills (usually more prevalent when it's raining) as well.