I have a 1991 honda that runs fine but after driving it for a little bit it just dies. I've already chagned the main relay and it still does it can anybody help me.

IAC (idle air control) might need cleaned... does it just sort of stumble and die slowly as the rpms get lower, or just cut off suddenly at idle.

Or is this shutting down at higher speeds?

Replace the igniter and coil. Apply silicone heat transfer grease to the back of igniter.