Its your EGT causing it. When it opens it pumps that hot exhaust back through the intake. Watch your intake air temps at the same time. I bet they will jump crazy too.
It might be the ECM is regenning because it does not see any sensors, It may doing regular burn offs now. Without your sensors, it's hard to say. Could be driving the ECM crazy. It wants to "Run Home to Mama"
Since you made your own DPF, why not put the sensors back in? It won't be that hard and it will tell if what I am suspecting is right or not. Then the ECM has all it faculties.
I missed that the first time. OOPS