Yes, the vapor locking would typically happen when at a stop sign or stop light. I'd have to push the car off to the side of the road and let it cool down for 20 minutes or so.
I was told that vaporing locking was a common problem for the 914. When I had the car for a year it was a constant issue. It was great in winter. Well, mostly great. When the brakes got wet, the car didn't want to stop all that well. Other warmer seasons I had to plan and be careful not to strand myself.
For what ever reason when my father drove the car to work, while living in hot Florida, breaking down wasn't as big of an issue. Vapor locking happened to him but not as frequently as it occurred to me while in Illinois. We never could figure out why that was. I tried different ideas I remember. The big one, where I thought for sure I had solved the problem, was moving the fuel line farther away from the engine. That wasn't it. Eventually I had enough and traded the car in. Ironically, as I was trading the 914 in, another couple were very interested in the car and I believe bought it. The sales lady I was with was joking about it. If they did I hope they got the vapor locking problem fixed. I was told of a pricy fix for the problem but forget today what that involved. It was my first car and I remember it fondly for that and joke about its many imperfections.