"And yesterday, the engine 'indicator' came on. I made a garage appointment for this afternoon, during which I expect to spend time & money."

You know many auto parts stores, at least around here, will run the codes for you. One time they ran them and it was rear O2 sensor slow to respond and they suggested cleaning it. I did and it worked, never a problem after that.

"The last
time the light came on was a major repair (cheap part, but lots of labour)to something deep inside the engine that adjusted valve timing based on load, etc. "

So you have variable valve timing. Yup, a bit expensive to implement but is really great for performance. I experimented with it before Porsche even came out with it I think. I had this Pinto and found when I timed it one way it had oodles of low end torque, I mean you could slip your foot off the clutch at idle and it would go. However, no matter what gear it was in it would only do about 45 MPH.

Timed the other way is seemed like a gutless wonder and feather the clutch or it would stall. However when it hit a certain RPM it really started to move. I mean really move. It went faster in first gear than ever before. Luckily I did not blow the engine.

I was lucky the way the (BMW built) engine was, the cam gear was at the top and the tensioner was easy to get to without removing anything as I had left the cover off for this purpose, being the experimenter I was. I was able to change the vale timing in a minute without disturbing anything else, even the ignition timing.

"Apparently, the garage paid the bill, not Ford. "

Good, everything is expensive now. And as far as I am concerned it is part of the engine, I would have considered a suit or mediation with a consumer affairs arbiter. To claim otherwise would be like saying speakers are not part of a stereo.