1980 450SL Fuel problem

[450-OYA]

We are moving and after driving the car through several states without any problems I am within 100 miles of our new home, right after refilling the gas tank and getting back on the freeway it begins acting like it is vapor locking. I exit, barely, and when i Take my foot off the accelerator, it dies and would not restart. After waiting 20-30 minutes, it restarted but was still acting the same until it died again. All gauges read normal, no overheating, good oil pressure, etc.. where do I start looking? Thanks, jb