Ignition module

I'm not sure which one it has, but it's either a torx or hex head security screw. These are available at certain tool or auto parts stores. It sounds like your problem might be the module, like you said, but it might just need dielectric grease on the module where it attaches to the distrbutor. This grease keeps the module from heating up which could cause misfiring. This grease is available at auto parts stores.