P0321 Error in 2010 VW Transporter: Engine Misfires, Stalls, and Enters EM Mode

Hi everyone, I recently encountered a recurring issue with my 2010 VW Transporter. After driving over 120 miles on a rainy Sunday night, I left the van parked in the street. On Friday, after driving a few miles, the engine management (EM) system activated, causing the engine to shut off. The vehicle would restart but immediately misfire and then stall. I took it to the garage, where they replaced both the fuel filter and the crankshaft position sensor. After these repairs, the van still ran poorly and eventually died again. At that point, the P0321 diagnostic code appeared when starting the engine. I managed to drive to the garage without any issues while the EM mode was active. However, once I turned off the system or restarted, the P0320 code would clear but return shortly after — accompanied by intermittent misfires. I recently replaced the rear brake light as part of a maintenance check, though that doesn't seem directly related. Given this pattern, I'm now suspecting an issue with the wiring harness or sensor connections. Any experience with similar P0321 issues on 2010 VW Transporters? Could it be a faulty ignition coil or loom problem?