I am concerned that if this goes on too long, too many tangents
will be followed and people will think I have lead them astray
(though that is exactly what happened to me and the technician,
we all thought the same things you are all thinking).

If you don't want to know yet, I am adding a bunch of CR's
before the answer, so don't look ;-)

Answer: The small fuel line between the fuel pump and the

accumulator was clogged with very very fine black

dust, almost looked like graphite oil (wow, can

you still get Arco graphite oil)? Also in there was

pieces (tiny) of plastic, whitish - probably from

the in-tank pump. The black particles were from the

rubber fuel line, which the technician thinks was from

crappy gas or the PO adding Dry Gas all the time (he

says it's very common - many Volvo owners "mean well"

and pick some up at Spags).

What was happening was that the little plastic pieces

would clog the line from time to time - causing the

bucking, etc. and then when I leaned on the pedal

the flow plate would rise a bit, requiring more volume

which the clog wouldn't allow. This is why I could keep

a certain speed, but not accelerate.

As time went on over the next hour, the plastic piece

really lodged in there and then the little black

sediment would clog the holes around the piece. Finally,

the car shut down totally. But, if you stopped it for

a while, the black pieces would probably fall back and this

would let the car start, but not run very well, if at all.

The simple test was to disconnect the fuel line at the
accumulator and see if fuel came out under pressure and
then ditto where this little line connects to the pump
(which of course was the last thing we checked ;-).
Laziness prevented him from checking these things.

Hope you didn't feel I led you astray, it's tough to give
hints without feeling that way.