Ign mod is in the left front (drivers side)of the engine bay. From memory, I believe it is a box about 4X5 in with 2 or 3 round plugs on it. If you want to make sure it is not causing the problem, just unplug all the plugs and turn on the ignition switch. If the fuel pumps still run, then the ign mod is not the problem.
If the above doesn't help find it, let me know and I will take a picture of one and send it.
84 500 SEL (307,xxx miles)