Seeing as how we have thus far thrown everything but the kitchen sink at the problem,.... grin2
I'll add my Canadian nickel...

Does your car have a ballast resistor wired into the start circuitry? if so, verify that it is functional.
The condenser is also a viable suspect /culprit. thinking
I share your frustration, Good luck! thumbs



Bert & B1800
"Tis well enough to know how much to know; and when to know, not to know, too much."