Chevy S-10 OVER IDLE

A friend of mine owns an older model chevy s10, manual transmission. Called me the other day and was having problems getting it into gear. The resivor was empty and so filled it with brake fluid and clutch is working again. BUT, the truck wants to run away from you. When you shift in to first and let out on clutch, foot OFF the accelerator, the truck barks the tires and takes off and will also do this again shifting to second and never touching the accelerator from sitting still to first, then seond. He lives in town and been driving this truck like this awhile I am guessing and I just think it is odd that it is idled so high or over reving itself. Any help would be appreciated, Thanks!
Rhug129306@aol. Com