'88 740 turbo volvo w/ b230ft engine

I've had it for a year now with no significant problems.I have had to replace to

alternater,and that's about it.I have put about 50k miles on it this past year.My

problem is this,I was driving on a trip down south with my wife and daughter,about 4

hours into it,the engine just dies completely.Now,it has done this in the past a couple

of times,all we have to do is wait 20 mins or so,and the thing starts back up with no

problems and runs without fail.This time it didn't .I ended up towing it to a shop,where

the little mechanic seemed somewhat knowledgeable.He thought it was either the

ECU(computer) or the Mass Air Flow Meter.Upon my return to the shop the next

morning,he had the car running,he said he did somwething to the inerts of the mass air

flow meter(he had the plate on top pulled off) But I didn't see anything

appearant.Well,when I pulled it out of his lot,with acceleration,the engine coughed.I

noticed,when the turbo boost gauge needle was in the yellow(positive pressure)the

engine started to sputter.When i returned home with the vehicle,I drove it around the

neighbor hood,as lond as i kept the acceleration low,with the boost gauge needle

below the yellow,then the car run pretty good,when i got boost,thats when the car

would start to sputter.Hopefully that's not coincedental.I am an aircraft mechanic by

trade so I know the princeples of the engines and I also own a 240 of which I do all

the work myself(I'm liking its non-turbo engine alot more).

Anyways,anything you can tell me,would be much appreciated..Also,don't know if this

is related,but when I first turn the car on,the voltage is always low,even when I had the

original alternater.In the cold,I would have to wait up to 10 mins before thelights

would work on the dashboard,the running lights would come on,but the dash would

be blank with the bright light signal light up only(the running lights would be normal

though).

mike thorjusen