99 Ford Taurus Power Distribution Box issue

I have a 1999 Ford Taurus SE 6cyl engine. There appears to be a short or bad connection in the power distribution box in the engine compartment that houses the starter and other relays. Originally you can hear it spark (but not see it) in this box and the engine would just shut off. It was easy to create just a finger moving the box and the engine shut down (didnt always here a crackle/spark). Took off the covers top and bottom and replaced the main relays and generally "pushed" everything together real tight. This significantly helped hard to create the problem now but it does still happen at times. Not sure if it is a loose wire or a bad contact.

Question: I can't find this part "Power distribution box" on line anywhere though this is what the owners manual calls it. Any thoughts on the cause/resolution of the problem? Any idea on cost and complexity to fix? Can the box be replaced or do you have to do a major wiring harness change?

Thanks in advance for any help you can provide my girl is going to be driving this car and I don't want her losing the engine/power steering /breaks while driving let alone getting stuck somewhere.

You really don't just replace those because they have to be assembled piece by piece and you would have to repair any wiring connection problems separately or replace the whole harness anyway. You just need to get at the bottom of it and isolate the exact source of the problem and repair it.