'84 500 Euro dies suddenly in traffic, won't restart for 5 minutes
 

This problem occurs randomly when hot, after a couple hours of driving in stop and go with no warning. Sometimes, the car feels like vapor lock where it won't accelerate and then suddenly catches and takes off! Then it is normal for a awhile. Already recently changed the idle valve on the intake manifold, the fuel pump and filter. Any ideas? Greatly appreciate any suggestions.