Volvo: 97 Volvo 960 electrical problems, alternator problem, volvo specialist

Question
Hi
I have a 97 Volvo 960 wgn and have been having off and on problems with electrical/transmission systems over the last 6 months or so.  Problems come and go, but it seems to have worsened lately.  My volvo specialist has had two efforts to fix this, but has only replaced my battery (which they said had a short).
Two problems that seem interrelated:
1) Several times, usually at night, when I flip the highbeams on the car's electrical system goes haywire.  The radio turns off then comes back on, the lights dim a bit, the tach jumps up and down (like the car itself is shutting off and on), and the transmission arrow on the dash flashes.  The car lurches like this for 10 seconds or so and then rights itself and keeps going.
2) Lately, the transmission seems to be 'searching' for a gear.  At a constant speed, car changes gears up and down.  Problem almost seems electrical.  Only occurs after driving 20+ minutes.
I had the transmission serviced recently and they found the fluid clean and everything looking great.
It seems like the car sends power surges.  I asked about the alternator and the repair place said they usually die all at once, not slowly.  I also understand the voltage regulator is a part of the alternator and can't be replaced separately?
Does these problems make you suspect anything?  I appreciate any advice you can offer.

Answer
Hello,
this problem seems to me as an "alternator" problem, I mean you are right while you suspicious about it. You should replace it wiht new one. Or if you can find a repair-shop, it can be repaired but in my opinion for them to test the alternator is not easy, so they can not understand which part has problem.
However, to understand to be sure about alternator I have a recommmendation for you, alternator charge level is approximately 13.8-14 Volts, start the engine and measure the voltage level from battery, it should show that value, you say your problem occures approx 20 minutes later, so approx 20 minutes later this voltage level will decrease to 10 Volts or less, this will indicate that your car will die like at the your problem. So that means alternator has problem.
You can be sure about it via this way.
Regards...