If this started all of a sudden, suspect the master cylinder. If it happened gradually over time, suspect the brakes are out of adjustment. Star wheel adjusters can become rusted tight, and cables can brake. Grooves can form on the backing plates where the shoe frames ride. Those can prevent proper shoe movement that initiates the adjusting procedure.
If this started shortly after replacing any brake shoes, be sure the ones with the shorter linings are toward the front of the vehicle and the longer linings are toward the rear.
Check for rusted parking brake cables too. If one is sticking in the partially-applied position, it will prevent the self-adjustment from taking place.
When two pedal applications in a row produce a high and solid brake pedal, it's because too much brake fluid is being moved before resistance develops. That means the shoes are moving too far due to misadjustment or the drums have been machined beyond the legal limit.
I can't find any reference material for this vehicle. If none of these suggestions provide a solution, try to post a photo of one of the rear brakes with the drum off.
Sunday, June 8th, 2014 AT 7:46 PM