Stalling on MS3 Pro mini

We have in our shop a 1959 Volvo 544 with a power train from a Mazda MX5. The motor is fitted with a Turbo and the Megasquirt MS3 pro mini fuel management system.

The tuning is good, and the car idles and runs great. The car has a concern when devices are switched on and off. In particular the windshield wipers and cooling fan for the radiator. The car is fitted with air conditioning and uses a trinary switch to control the fan with a/c high side pressure. When the a/c pressure reaches its threshold, the fan turns on with no issues. When the fan cycles off the car stalls. When the windshield wipers are switched off from the high-speed setting the car stalls. Car runs correctly when wipers are switched off from low speed. The car has no reaction when wipers are switched on in either speed. I suspect electrical noise is interfering with the ECU and interrupting the cam and cranks sync, by the way the car cuts off, as if the key was turned off. I have checked and repaired ground locations. All power and grounds are in the locations recommended by the manufacture. Dip switches in the ECU are on. The crank sensor is located at the crank pulley and the cam sensor is on the valve cover in front of the cam gear even though we are told this motor was from a 1993 model. The car had other chassis wiring concerns, but all have been corrected, and this condition was present prior to those repairs. Harnesses all seem to be clear from any motors and coils.

Has anyone run into this before or have any advice on what I may be missing?