Volvo Repair: 98 VOlvo S70 glt engine keeps dying while driving, volvo s70 glt, temp guage

Question
If you can help me with this Ill give you my first born whatever.............I have a 98 S70 glt and when ever the weather gets warm the engine will start to vibrate and eventually spin down and quit altogether.  No service engine light comes on, it doesnt usually happen while the car is sitting at idle, it usually happens about 5 miles into a trip depending on the outside temp.  I took it to the dealer and they thought it would be the throttle control box, but it isnt storing any codes in the computer.  I had the fuel pump replaced and that didnt help either.  Whenever the service people have it, the problem wont replicate, so they wont work on it.  Any ideas?  THe temp guage never gets above halfway, it happens when the AC is on and when its off too.  Im about to pull my hair out.  Any help would be great!

Answer
Michael, some 98 have the throtle units, some dont.  I need to know which one you have.  Does yours have a cable or not?  This is one of those fun driveability problems.  If I were a betting man, and assuming your car is not a ME7 fuel system, I would say a intermittent cam sensor problem or an ect sensor.  If you do have a ME7 system, then Im with the dealer, I would have to have the car do something for me to diagnose it.  They are just being lazy and not spending time on the car.  Its all about Money at the dealer and those guys want to suck up all the gravy work and leave the pain in the neck diag work alone.    It may also be a Air mass meter.  If the dealer thinks a throtle unit, then they should have changed it because there is a recall on those units.  Hope this helped.  Roger