If a coil was trying to go out would it keep the car from idling?

 

In my experience coils either work or don't. I've heard of other scenarios, but I've never seen it. Swap it with a similar coil and see what happens.

 

Weak spark makes a car hard to start, but I don't know if that would affect idle. I doubt it though.

 

I am going to try that tomorrow...one of my friends has a coil that I can use that is the same as the one I have. The problem started when I came back from a three week trip and upon my return my car would not idle, even though it would before I left. I had the carburetor rebuilt/readjusted as well as new plugs, wires, and gas. The only thing that changed after all of those "fixes" was now all of the cylinders actually fire.