Apologies everyone.... soo it looks like the electrical fault was a Red Herring. I don't think they did their due diligence, or even listened to what I asked them to do; which was check and reinstall the intake assembly.
After checking for continuity and more or less verifying all wiring was in good order I viewed the Merc codes using a newly acquired scanner. I then cleared the codes and drove around to see if they would come back, they have not, and I had the shop verify. On their initial diagnosis they said the codes came back immediately after clearing (possible that they never cleared them?).
In all likelyhood those codes are related to OBDII codes that pop up when the MAF or MAP are disconnected which often happens during troubleshooting. I then clear the OBDII codes but didn't have means to view/clear the merc codes.
---------------------
Van still runs poorly. And to clarify I can still drive it at maybe 80% capacity. The turbo does fire at low speeds but getting above 60 uphill on highway the RPMs hit 3-4K and turbo still doesn't fire. When it does fire at low speeds I need to press much harder on the gas pedal than previously. I can also hear it spooling at a much higher pitch, which sounds like air is escaping.
I mention this because shop said that they are surprised no "low boost" codes show up. They did a smoke test the first visit but never tested under load. I would bet money, given my symptoms, that the air only noticeably escapes under load. That makes sense right?
Anyways I'm curious if these symptoms align with the assumed mechanical assembly issue?
- Symptoms came up immediately after glow plugs and never had issues previously
- Symptoms did end on a few occasions when I reinstalled the pipes with "no gaps"
- likely stopped when boost pressure moved pipes and created a gap
- No "low boost codes" because boost is being built but just not as efficiently