I had some trouble with low power and occasional stuttering.

My mechanic said new ECU. Sent it to Darrell instead, who performed
some marvels on it and tested it.

Now my local mechanic put in the ECU and ran his scope on it and says
there's a bad ground somewhere. He replaced it with another, and
there was no problem.

Might the problem be with the mechanic or his scope? Or should I
trust the scope?

Having gone the Darrell route, and recognizing that the alternatives
are do nothing or get a rebuilt for $400, I think I know what I'm
going to do, but I don't really want to learn the hard way (that
would be another three hours in Barstow and two in Needles).

All free advice is welcome!

TIA,

Neil in '87 Westy which runs fine for the first hour, haven't tried
the second yet.