Intermittent Issues 89 Volvo 760 Turbo Wagon

This is probably going to tough to nail down over the net. Someone may be able to jump in and help, but if not I'll make this suggestion.

Get hold of the local snap-on tool dealer.
www.snapon.com
This guy should know the good capable shops from the bad. Tell him what you have, not everyone is "volvo friendly"
You need to be patient with this. Let the shop owner use it as his personal car until the problem acts up and they can find out what is happening while the problem is present. You need to give all info possible. IF he is not familiar with iatn, ask him to post it there or work in one of the chat groups to help solve it.
ww.iatn.com

I did fin a technical service bulletin about an udated eprom, but i can't imagine the dealer overlooking that, unless it doesn't really apply after they considered it. Ask them, it won't cost anything.

I am not a mechanic at all can you tell me what a eprom is?

Also I asked them this morning if they have checked the following. Do these sound like they could be the issue?

Hall Sensor or RPM Sensor
Ignition Power Stage (Power Module??)
Throttle or Crank Position Sensor
Some sort of electrical connection that goes to the injector.

My help to you is limited. I am not a tech either. Isee alot of cars and see alot of solutions and do a ton of research. Frankly when i see a volvo, I shudder. However, i earnestly try to help however I can. So I don't know too well about your questions. I would rather appear to be dumb and honest, than stupid and transpa :)
an eprom is essentially a computer chip as I understand. I "assume" the e is electronic. The prom is an acronym for programable read only memory. Much like your pc.

I have similar problem w/ 1 I am working on. I have an '88 that came in dead. No fuel or spark. I fixed both, started it up and it ran fine about 30min. The next day come in and it wouldn't run, only cranks. I CK things 2 find no spark. I replaced the "Jetronic", still no spark from the coil. I replaced the "power stage" module and coil, still nothing. The original coil is OK. I need a better wiring diagram cheap. The 1 I have 2 work w/ is a Hanes 80-87... partially in german and non conclusive. I can read german that is not the problem. I have things that the diagram does not show, as well the diagram shows that I can not find. I have encountered different versions of vehicles wired not the same as mine. Pls help. :x

Ground is good?

Thx 4 the Image. I tried the grounding thing. Still no change. :x

on older 700 series volvos a lot of fuel gauge not working/instrumentation problems/starting/charging problems are caused by the printed circuit board soldering starting to break up due to the location being next to windscreen demisters.
these are notorious for failure.
tey can sometimes be successfully resoldered on the back where the wire links connect but are quite fragile.
i have just yesterday recieved a replacement -pcb volvo call this a lighting plate- for my 1990 760 gle turbo diesel estate car.
could not get one throughvolvo so located a volvo classic car dealer agent who tracked me one down in gothenberg.
i had a new volvo 360 that just died intermittently on me,left it for 5 minutes ,started up and would not happen again for 6-7 days,then same thing again. went back to the dealer for a week this also turned out to be the problem that time.
the new pcb board on my 760 is manufactured in japan.
volvo tend to say these pcb boards are not a problem,but through the uk volvo club have concluded they are a major source of speedo/fuel gauge/engine temp/abs light failure problems.