Signs of a bad Ignition Module
If you cranked the engine very long trying to get it to start with a bad module it could have fouled the plugs. Did you have spark before you changed the module? If you did there is a wild goose chase in the making. Like mantta said, you usually don't get any warning with a module. If the fuel pressure regulator got stuck or a MAP sensor failed it would also cause a rough idle on an engine that otherwise runs well.