88 cabriolet stalling

My VW has a problem with stalling after it has idled for awhile. It
doesn't do it when you're driving, only after you've idled. We've
replaced the fuel pump, fuel filter, checked the transfer pump, the
electronic control unit, and it still dies. The fuel pump puts out
40 pounds of pressure when it stalls, but it acts like it's not
getting any fuel. If you let it sit after it has stalled for 30 -
45 minutes it will start right back up. If anyone has any idea
what's wrong or where I can find help, -please- let me know.
Thanks.