Its a cable clutch if I am not mistaken, right? You may try to adjust the clutch by going to the firewall on the drivers side. Right next to the brake booster is a cable coming out of the firewall and it has a sort of daisy looking large bolt on it. This is where you adjust the clutch. Grab the cable housing and pull the cable away from the firewall. When you pull the cable, there should be about 1/16 to 1/8in of an air gap between the daisy adjusting nut and the rubber spacer on the firewall mounting cable.

See below
cable clutch adjustment.jpg