I picked it up from the shop today. They decided it was a key issue but I have low confidence in what the decided. I think they just decided not to screw with it and held it a few days. $180. Should I keep looking for a mechanic? I might try disabling the subs and amp just to see if that helps any. Got nothing to lose

 

I had a broken temp sensor wire on the coolant crossover/thermostat housing shut a vehicle down, no start, etc.

You should go through and inspect every connection including the ground cable on the battery where it connects behind the fuse box.

 

So I paid another shop $200 who came up with nothing last week. But I did unplug her subwoofers and amp, and so far, it hasn't died. I think I may be onto something.

 

....or maybe not. Hard to prove the negative.

You needed to be able to repeatedly produce it before, in order to diagnose and then determine if it's fixed now. I hope you are right, but mostly I just hope the symptom was erroneously reported, because a sub-woofer killing power to the entire vehicle would be disconcerting to say the least.

 

Depends if it’s factory or a badly installed aftermarket set up

 

Please elaborate....what can the sub take out, electrically, that would cause the engine to lose power?

I've only ever heard of this happening if the Alternator goes out...and even then are signs (lights illuminating, sluggish behavior at low RPM).

 

Power drain. Basically a brown out. Sub/amp pulls so much power the alternator and battery dip low enough to shut it down. Very possible.

 

Well, looks like I missed again: She reports the car had trouble starting this afternoon. I am actually ENCOURAGED by that as it gives me some more clues. Fuel pump, ignition, ???

 

...I can see that since it wipes out the alternator.