This summer when I was returning from a camping trip I had to stop on the highway for an accident. After sitting at idle for a few minutes I turned the engine off. When I started it back up (15-20 mins) it wouldn't idle. It ran fine off idle, but it would always die when I let it idle.
After driving for a while it began to idle ok and everything seemed fine. But an hour or so later when I hit the city, it started again when I pulled up to a light. When I got home I adjusted the idle up to keep it running but I discovered that the idle was surging high and low. It was the low that was causing it to die. It did this off and on for a couple of weeks, but now it does it all the time. I also discovered that it starts up and idles perfectly when it's cold, but as the temp comes up the surging begins and only gets worse.
It seems like a vacuum leak to me but I can't find one. I checked all the connections with brake cleaner including the carb and entire intake manifold. No leaks.
There are 2 thermo vacuum switches, that I can find, and disconnecting or bypassing them has no affect.
Any ideas?