Can you confirm egr control, looking at airflow and confirming with o2 output?
A few things you need to confirm, but first does it run and can you increase to fast idle?
If not, just slaken the dpf off while you do some tests.
You need to confirm the output from the O2 sensor, is it a four or five wire?
This is used for closed loop control of egr, if it's not working properly then you won't get correct egr operation, then on the flip side if the egr isn't working, you won't get correct o2 output.
EGR should be operational at idle so unplugin it will affect airflow and o2 output
Come back with some results and deal with the dpf sensor last
Chris