MAke yourself a bunch of short jumper leads with male spades on each end.
One at a time bypass all of the switches with the jumpers starting with the seat switch.
If you get to the end and the engine still cuts out then there is a short in the wiring.
Most of the safety wiring is ground wires so a short will not blow a fuse or cause a fire but it makes finding a short really difficult.
I use a test lamp with the clip on the + terminal and go looking for ground where it should not be.
This requires all of the jumpers to be removed and every connector checked for a ground.
It is prudent to pull the blower housing off and remove the kill wires to the coils to prevent accidentially sending 12V down the wire and the block probably needed a clean in any case.