Since DPFE sensors are faulty enough to cause issues but not enough to trigger a DPFE related code all you'll get are EGR related DTC's. Misfiring could be one of them as DPFE is reading incorrect data and commanding the PCM to open the EGR valve; that would surely cause a rough idle too.
You could try feeling the vacuum line on top of the EGR valve to see if it has excessive vacuum, if it does then you've found the problem and DPFE is the most likely culprit. A small amount of vacuum is acceptable at idle.
I'm thinking you could just unplug the DPFE sensor, start the engine and take the van for a drive. The PCM should compensate (up to some point) for the lack of input and drivability problems should diminish or go away if that's your problem. Be advised that disabling the EGR system for a long time can increase temperature in the combustion chambers and elevate NOx readings so, use this information only as a diagnostic method rather than a solution
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There is a procedure in which you can pull vacuum on the DPFE REF hose and backprobe the connector in order to read the voltage readings, the only problem is that you can actually damage the sensor by pulling too much vacuum or creating excessive pressure. I'll see if I can find it for you if you want it.
I have no idea if the revised isolator bolts can go bad, but having a look at them wouldn't hurt. Maybe someone else knows a definite answer to this.
Oscar.