electrical short

I`ve got one for you guys that are electrical ''smart .''
I developed a short somewhere , the car runs fantastic ,( 505'' , 68 fastback) , has been rewired from day one , even before I built the engine , has been running great for about 2000 miles .
It has developed a short that completely shuts it off when I hit a bump , it does (so far restart immediatly if I am boing fast enough for trans. to drag the engine over. Or I can slip it in neutral and it will restart immediatly.
I had it running ,up on blocks , well warmed up and was wiggling wires ,when I wiggled the power wire to the ign. switch it died , OHBOY , thot I found it , and rewired the power connector! Took it out to fill with 93 oct. and got out on the hi way hit a transition bump going over a bridge
and it died , but was going probly 75ish ,and it restarted , took her home and quit for the day , bummed out bad !!
I have checked and replaced , or tried switching a lot of parts , .even sent all the major fuel inj. pieces back to FAST to check , no problems there .......

WHAT are some opinions on my problem ? thanks in advance .
Car really gets with the program untill I hit that bump ... ....Bob