Volvo Repair: older 740 just dies at stop signs, vacuum leaks, vintage volvo

Question
This is an '87 740 turbo wagon automatic with 117,000 miles that was well maintained by my father-in-law but not driven much in the past few years. Now, it just wants to die when I come to a stop and sometimes when I am driving but slowing down or trying to speed up. Then it will start right up again. Yesterday, after not driving it for a couple of weeks, it barely ran at all. It seemed to miss-fire a lot and had very little power. However, if I put it in neutral, the engine responded just fine. But under load, it sputtered. After driving it for a couple of hours, it was doing much better - only died occassionaly coming to a stop and would idle for extended periods while I waited for the kids.

It seems that the engine and transmission are not talking to each other very well. On advice of a mechanic acquaintance we replaced the fuel pump relay but that does not seem to have helped. Our other mechanic, who does not regularly service older Volvos, has not been able to find a problem. I suspect they simply do not drive it cold or for any duration. I have also noticed that the automatic speed control does not always want to set either but that may be operator error.

I would like to figure out what the problem is without throwing more new parts at it in hopes of salvation. Do you have any ideas on how I should proceed? I can turn wrenches but do not have any special tools. Do I need to find someone with special equipment to diagnosis this vintage Volvo?


Answer
Greeting G,
          There are sooo many reasons why your 740 stumbles under load...and stalls while stopped on occassion...vacuum leaks...failed connections..faulty computer module...fuel related problems..faulty electrical connections.
          Often it is better to go to Volvo dealer who can read engine/electronic systems...you can then decide if YOU want to do the repair....many non-dealer repair shops can plug into these systems with diagnostic equipment to accurately read your problem...
          It is ALWAYS BEST if you seek out opinions..rather than spending lots of money on unneeded parts...
          Good luck,
                  Bilbo