It may not be a 5 minute job, but if you are prepared to run around in a rat-rod like fashion at least knowing the underpinnings are good then it may not be as much work as it could be.
Pay 500, rip everything out, ecu flash for 250, scrap the rest for ~250 round here at the moment, and still less than a Tdi build.
And a whole lot more fun.
Just throw another option into the pot, is it possible you have a mix of tdi and V8 pipes there?
The carbs on a V8 used metal fuel line to go between the two carbs(if I remember correctly) , perhaps one or both are not tdi at all...
Charge controller controls the voltage, so I would start there.
That said, some of these controllers have a higher voltage/frequency mode to help maintain the battery, often run just once a month, it could have been that?
Worth checking the manual, I would think.
Er, really?
We've had massive subsidies, clean air zones, sustained fuel duty, exemption from congestion charges and zero licence costs.
Whilst they are reducing, the ev manufacturers are still being propped up with tax payer funds.