LS Swap - Erratic Dakota Digital Temps

[1bad396ss]

Dakota sending unit in passenger head. Everything seemed to work fine during startup and burping the system then it pegged hot instantly. Thought I had a grounding issue, but suddenly started working. Now erratically working and not. Wiring of this gauge and various other BIM units seems sound. Is it possible for a air pocket to cause the issue? I ruled any sort of hear soak issues from header and downpipe our when it started to work during hot operating conditions. When working temp seems dead on with expected temp. Any thoughts or pointers appreciated.