Car dies while driving (sometimes)

1992 VW Cabriolet w a 1.8 Liter Digifant II 5 speed. It just dies when it gets hot, no warning just dies. It's my daughters so I tried to fix it thinking it might be the ignintion module, I replaced it (small box mounted on the computer on driver side near window wiper motor). The problem still is happening. The last time it happened while accelerating onto the highway just hit 60mph got to the 3rd lane and it died. After about 45 min I was able to start it up again and it happened again about 2 miles later. This time I towed it home, however since then it hasn't happend again (weather now getting colder), this time I have a spark checker ready to insert inbetween spark plug and wire (light). Am I on the right track, and if so where do I go now if it turns out to be ignition?

No I didn't check the Hall Sender, honestly I never new about it, what should the Voltage range be, and how do I check (ignition on/off), I imagin engine not running while testing.