95 DX won't start, losing power at speed.
 

First off, I'm trying to diagnose this for a friend, so I am going off her descriptions and will do my best to be thorough.

She recently purchased a 95 DX with many miles to get around. When she was driving at highway speed, she started losing power. How she describes it makes it sound like it bogged down, and giving it more gas didn't help.

Once she had stopped on the shoulder, the car would not start again. Headlights, and accessories run strong, and at a later date that car would not jump with cables going to a strong running car with a fairly new battery.

I believe it is the starter because it makes a "clunk" sound when you turn the key. I had this happen to me on a Toyota Echo, but it was more of a click. On the Echo, tapping the starter with a hammer to get the brushes to engage helped for a while until I got the replacement. Not so with this Civic DX.

I removed the starter and alternator (for good measure) and took them in to be bench tested. Alternator was fine like I thought. Starter engaged and spun really well, but came back as a fail due to failing the "Amp draw". Would this be enough to cause this issue? Would it cause her highway speed problems if the starter wasn't disengaging properly?

Anything you can suggest would be great.
Thanks