If you are getting 11 volts while the car is running, how does that pass the test? You should have 14 volts.
You have two grounds in play. A thin one which runs from the negative terminal cable loom to the sidewall right above the battery. The other one is the engine block ground from the battery. It runs from the positive terminal, down underneath the front of the engine to the bottom of the block, in front of your oil pan.
If you have ramps, put the car up and you can get at it from the front with a socket and a short extension. To truly check and clean your cables, this one has to be backed off of the block and checked underneath for corrosion. Either brush it real good, or use an electrical unit cleaner. Both the connector loop and the block area. Put some dielectric grease on it and torque that baby down real firmly.
Clean and grease all connections related to the battery, no cheating.
I have had my '95 for 12 years and 75% of the time something whacky happens that'* electrical (that can be dash, gauges, lights etc) or power cuts, it'* those stinkin' battery cables, or the bus ground for wires that run under your front door rails.
If you want to save yourself some headaches, do those battery cables twice a year as regular maintenance. That includes the engine block ground, because that'* the most likely culprit.
Oh, and BTW, don't Google the Net for answers on Bonnevilles or 3800 engines. The people here and BonnevillePro (OT:I'm assuming you two are friendly, Dan?) have been through hundreds of thousands of problems thread, they can diagnose problems on-line better than most independent mechanics can with hands-on. The reason is that they have heard so many things repeat themselves over the years, they are way more familiar with common problems than a mechanic who works on all different kinds of cars. (end of lecture).