88 190E 8V Intermittent Stalling

I have a 88 190E 2.3 8V that developed an intermittent stalling condition, hot, cold, after two hours of driving or right after you start it, it doesn't make any difference. Once it stalls you wait 2-3 minutes and it starts up and runs normally. Car stalls three or four time a day. Had it into the shop several times and they could not trace the problem. On a hunch, I rigged a test lamp to the fuel pump and found out that every time it stalled the lamp went out so I know the issue is related to fuel pump power. I put a 12v switched line in-line with my test lamp and it continues to run fine. I have a service manual which shows the fuel pump relay in the panel box behind the fuse box but there is no F/P relay in there. I don't want to defeat the relay since the pump would continue to run in the event of an accident with a fuel leak so I need to trace this one down. Has anyone else solved this type of problem before, and where is the F/P relay???? Thanks for any help.