Tach dies; motor cuts out unexpectedly

2001 Buick LeSabre Custom, 74,500 miles, automatic transmission, 2-wheel drive, maintenance schedule followed carefully, single owner.

This car, the worst mistake I ever made, is a shabbily built one, which has been one service problem after another.

The latest headache is symptomized by the tachometer falling to zero unexpectedly. Lately, this is also accompanied by a sudden engine stall, which can occur in Park, in city driving, and even after we've been cruising along on a highway for 45 miles, at full speed--without warning, the engine suddenly stops, the battery light comes on, the power steering is lost (and with it, most of the ability to steer at all), and, at 70 mph we're stalled and must stop, turn off the key.

Then we restart, the tach needle moves again, the engine runs--until the next stall. It's intermittent, and the dealer has no clue and keeps telling me he can't find anything wrong.

Sometimes the tach dies with a noticeable lurch, other times I just notice that the needle has fallen to zero and is lying there, dead.

I've had stalls at all speeds, in park, and when about to make a three-point turn going into reverse.

Each time, everything starts up fine again after I turn the car off and restart. The battery and alternator are okay--I've had them tested independently.

I've driven 80 miles in the morning with no problem, this past Sunday; on the way back, we stalled at 46, 56 and 60 miles.

I think that the tachometer is going too high--when it is running. I see, for instance, the needle going all the way to 5 when I am on an acceleration ramp--and I don't think that's normal for this car. I feel hesitation and lack of pep and power going up hills.

Finally, I feel rough uneven idling at first start-up in the mornings.

The stalling can go away for weeks at a time--and not happen at all--and then comes back unexpectedly. I'm unable to find a correlation with weather conditions, heat, humidity, etc.

I've had the dealer look at it twice, now.

Six years old, not even 75000 miles, and I have a car I can't rely on. Last GM car--last American car!--I'll ever buy, that's for sure!

Meanwhile, does anybody have a clue I can bring to the dealer when I bring it in a third time, in two days?