It has been posted before to mount a second condenser on the firewall so it is grounded. As soon as the car stalls and won't start put a jumper from the condenser to the coil nut on the passenger side of the car. This makes a new condenser (should work unless the first condenser is totally shorting out then it may not work...but an excellent quick check).
https://www.fordbarn.com/forum/showt...+2nd+condenser
Also does the horn still blow when car stalls? If not jump both terminals together on junction box...bypassing a bad amp meter.