I got some work done recently on my VX, including transmission service and fuel filter change. It drove fine about 50 miles after that. I then have cleaned MAF Sensor in attempt to get rid of "lean during acceleration" CEL, and went on what had to be a 200 mile drive. Engine shut down after about 30 miles right in the middle of freeway. All dashboard lights went off, headlights and emergency lights still worked. Engine wouldn't start after that, with no dash lights coming on when i turn the ignition, but the starter would engage (to no effect). Tried disconnecting battery and wait 5 minutes, but no dash lights and starter working repeated. I then checked all the fuses and unplugged / plugged back in all black cubes (ECM, Starter, etc) in fuse box. The engine then started but shut down again half a mile later, also producing check TOD CEL, lights. And then I was back to no lights on dashboard/ starter works situation. I then called AAA to tow me back home.

Can anyone advise on how to diagnose this? I have not looked at stored codes yet, but CEL light is not currently on (after reconnecting battery and re-pluggin black cubes). I read some threads here that tied similar problems to fuel filter, but my mechanic is very certain its not, and is an electrical problem. Appreciate any pointers, thank you!