Volvo Repair: Unexpected Stalling issues, dashboard lights, exit ramp

Question
Hi Phil,

I own a 1990 740GLE Wagon w/ a B234F 16 valve DOHC engine with approx 280000 miles on it. The car looks and ran great up until a week ago. I stopped for gas and once finished pumping, I tried to start the engine which would not. It would turn over but not "catch" After checking the timing belt I attempted to start it couple more times but it was obvious that it had made up its mind to not to. I was towed to my mechanic's who tested the ignition coil and there was spark. He then proceeded to tap the fuel pump and the car started right up. We went ahead and changed the pump and filter (Bosch) and the car drove fine thereafter and for 4 more days, until this morning. I left my house and everything was OK until the car had reached normal operating temperature. I made a quick stop and then started it up again, engaged transmission and drove for 100 feet at which point it chocked, spattered  and shut down. I attempted to start it again w/ no success. While getting my mechanic on the line, I had the ignition off and 30-40 seconds and it then started right up. I decided to drive it to his shop and it became a nerve testing ordeal as it stalled about ten times in less than 4 miles! Under my advise he changed the pump once again and the car behaved fine on a road tes. I then proceeded to take the car on a 30 mile business appt trip and did not notice anything on the highway until I started to slow down for my exit ramp. It then started to do the same thing.....rpm's erratic from almost 0 - 500, shaking, bucking, chocking etc. and dashboard lights going off and on the sign of the car being running and stalling. I put it in neutreal and it somehow revived itself. I called the mechanic again and he said to me over the phone that it sounded like an ignition coil mulfunctioning once the car got hot. It took me a good 2.5 hours to return the 30 miles and almost every time I came to a slow crawl or stop the car would stall.Highway speeds once again appeared unaffected (or due to the speed it appeared that way) and again once I got into the city thecar started stalling. My mechanic does not have the European diagnostics module for his computer. Any ideas what might be wrong with it? Thank you for your time and expert opinion.

Regards,

Harry

Answer
These intermittent problems are hardest to diagnose. It'll have to actually happen before it can be pinpointed. You said it happened right after filling up with gasand had no problem before, I hope you don't just have a bad batch of gas. This is a long shot, but i'd isolate that problem before going on. Recommend draining and refilling tank. I would also have your machanic install a set of fuel gauges and drive it until it dies again. The gauges will show if this is a fuel or ignition related problem.
If it is very sporadic and time is an issue, I would recommend replacing the fuel pump relay as preventative maintenance, it's not that expensive.
Also have him check to make sure the in-tank fuel pump is working.
Keep me posted.