Subaru keeps losing power and it's definitely NOT the alternator --?

I have a 98 Subaru Legacy wagon and have replaced alternator FIVE times in last 7 months or so – originally my mechanic (who has been awesome & doing all the replacements for free) thought the parts were defective, but last one came from a different supplier and only a month or so after installing, my car just died at a light this morning. Battery not drained, and mechanic was able to start it after had it towed there. What can it be?

FYI, bought the car used two years ago, so don’t know whole history, but was fine for first year or so. The first time I lost power, I think it really was the alternator (and snapped belt), so I don’t know if something happened or something was not reconnected correctly. (First time it broke was on a Saturday and my regular mechanic was closed to went to someone not very good – and if this is useful info beyond just complaining, when this guy put in the new alternator, he didn’t connect it to the battery, so I stalled out within hours of the “repair.”)

My mechanic is stumped and I am at a loss – don’t want to sink a bunch of money in if this is the beginning of the end of the car (mileage is just over 100k, though, so seems to young to die), but need a bit more reliability.

It’s amazing that someone would replace the alternator 5 times in 7 months without reaching the point where they call a time out to reason this out.

There’s not much info to work with as to how the alt. came to be blamed for this problem.
Have the alternators been checked and known for a fact (100% fact) to be bad?
The car died at a light but it it was running fine other than dying at an idle this could point to an Idle Air Valve problem.
Does the red alternator light come on before this problem occurs?

Just my opinion here, but I think someone could possibly be going in the wrong direction on this problem and is misdiagnosing it.
Your car only has 100k miles on it; it’s still a child at this point.

Sorry I can’t be specific here as a lot of detail would be needed but going through this exercise repeatedly does not reflect well on the person doing it.

When the engine dies do the warning lights in the cluster turn on? If not the problem is between the battery and the and the ignition switch. Possibly the switch is causing the trouble or the connection to it.

Someone needs to check out the systems to find out what is wrong, not just keep replacing parts. That is just repeating the same error over and over and wondering why you keep getting the same results.

Not only does it appear the mechanic is repeating the same error, you are getting to the point that you are repeating the same error (using the same mechanic).

Yes, as much as I love my mechanic, I’m definitely looking for second opinions – hence this post… And I know it’s not the alternator, so not replacing that again. Basically just looking for ideas that I can bring to whatever mechanic I take it to now. Have heard from friends that similar issues ended up being something really simple like a loose/bad spark plug, but have also heard that it could be a major electrical issue.