Mar 13, 2018 (2 years ago)
No real answer to this one other than a minute inspection of all wires/connectors and systems.
For example I had a Traffic in once that had been to I don't know how many techs.
Multiple fault codes and bad running.
What I ended up doing was to remove the engine wiring harness and bench load tested it.
Visual inspection of every wire once they had been cleaned with solvent.
Might sound excessive but I counted over 14 short circuits.
Some of which were just a single strand of wire poking through the insulation but this was enough.
Van ran perfectly after this and still does after over five years.
Now I'm not suggesting this is the same as your car but my point is your going to have to find a nut job like me to take this on,
And your going to have to put up with an extended and unpredictable time frame.
You know this,
There are no magic wands or silver bullets to fix this.
Find an auto spark and explain ALL the faults and what has been done so far.
Or trade the bugger in and be done with it.