MAJOR headaches - SOLVED
I thought I'd share this result just in case it helps someone else someday. I surely could have used this info a few months ago. Starting last fall, my Borrego started experiencing a series of seemingly unrelated issues with solutions elusive. Now that I can finally declare my problem solved, I want to share my ordeal as it seems to relate to a unique characteristic of our particular SUV.
1. At low speeds after a cold start, the vehicle would suddenly loose all electrical power for a second or so in the first few blocks of driving, occasionally reoccurring a few more times early in the drive, but not usually later after the vehicle was warmed up. Over time, I determined that it seemed tied to the first moment when I hit 20 mph after leaving the garage.
2. During trips when I reached highway speeds over 55 mph or so, around 2 out of every 3 trips I would get quick "lurches" or that would occur irregularly but often. Sometimes every 10 seconds or so, sometimes longer, sometimes less, but never in a repeatable pattern and not every trip. I worked with two shops on this. Since the lurches were felt vehicle-wide but not in the steering column I first though transmission (thankfully it wasn't) but the best anyone could come up with was misfiring cylinders so we replaced a few plugs and coils, but that did not solve the problem.
3. Every now and then I'd go out to start the vehicle in the morning and the clock was wrong and the radio presets lost, telling me that the electrical system must have failed at some point during the night, but yet seemed to be working fine at that point when I needed it, even during a cold MN winter.
The vehicle started all winter, but this spring, I took it into a shop and the battery was bad, so they replaced it (still under full warranty). At their suggestion I took it to another shop and had the alternator tested, and that was also deemed bad and replaced. Sensing that all my problems may have been electrical, it was with high hopes I drove the vehicle around and hoped that all my problems would be gone after the new battery and alternator, but no. Not only did 1 and 2 above still keep happening, I would still find the clock/radio reset in the morning on some occasions. Fortunately, the vehicle was still quite usable in town so I continued to drive it to work (a mile or so away in town) and the saga continued.
After work one day, I went out to drive home and my Borrego wouldn't start. Turned the key and it was dead. Cold dead. No electrical at all. I've certainly been around the block enough times to know that this often means just a bad battery connection, but a quick check showed them to be fine and, remember, the battery was only a week or two old at this point. I had the vehicle towed to a shop and the next day they informed that the ground connection was bad. Assuming I understood the guy correctly, he said that our Borrego electrical system only has one ground for the engine and it was very corroded and is connected to a rather flimsy piece of metal to begin with, and thus the entire electrical system had been going in and out and at that point had failed altogether. They re-built that connection (and an even better one, so I'm told), and ALL MY PROBLEMS VANISHED! Further, I can't help but wonder if the bad ground is what brought about the early demise of my battery and alternator.
Summation: If you suspect anything electrical with your Borrego, make sure the shop checks the status of your engine's ground connection. It apparently isn't towards the top of the list of things most garages check (I had used at least 3 shops in this ordeal), but Borregos apparently are prone to this failure.
Still love the thing, glad to have it back in full use again!