Ok I know what your talking about. The part stores lists it as an "EGR vacuum solenoid.

Any way to test them?

 

I grabbed another evr off a low mileage Taurus at the j yard and it seems to have fixed my problem, at least while revving at idle. I will give it a good test drive soon.

Thanks for the help

 

Drop to view my post on p0401 99 navigator. Just tested my DPFE koeo read 7.4 volts. Started engine hooked up hand vacuum to top of egr valv-before vacuum 7.4volts applied vacuum 5-7hg fluctuated between 3.8-7.5volts. The wire tested was the top wire on the connector. Ordered a new dpfe the one tested was a week old.