Toyota Repair: clutch problem, clutch master cylinder, clutch slave cylinder

Question
I have 1991 Corolla with 173k miles.  The engine was rebuilt at about 120k and the (original) clutch was replaced at that time.  It shifts between gears while moving just fine.  When starting out in first or reverse it wants to jump into motion as I'm letting the clutch out which mostly causes the engine to kill because I don't want to feed the accelarator too much and jump into an accident.  The clutch has to be held in to start the car and that all works fine.  But if it is in gear and the clutch is held in, it may start to go at the slightest movement of the clutch pedal.  What part of the clutch is likely going bad, is 50k miles a little soon?  Any guess about how much the repair should run?

thank you

Answer
The clutch is operated with hydraulic cylinders,there is either an external hydraulic fluid leak or an internal problem, the most common problem is a leaking clutch master cylinder, check on the inside where the clutch master cylinder attaches for a fluid leak, also check or replace the clutch slave cylinder if it is leaking. If one of them is leaking replace them both anyway.