loud knocking/clicking.

[atlamm66]

i just bought a 1992 240sx manual and when i was driving it home it started to make this clicking/knocking noise(it was a close friend who sold it to me, he had no clue there was going to be anything wrong with it). well i put oil in it and lucus oil additive. it still made the clicking sound.well whenever i put it in gear and took off the noise was not as bad(plus my cluch was slippin a lil). i took it for a couple more spins and all of a sudden everytime i shifted my car stalled or died it seemed like.i started losing power, tourqe ect. so i brought it home. now when i start it it just sounds like a marble under the hood. i cant tell where the sound is coming from...all i know is that it is not the top end. i would be able to hear that. one of my friends thought mabye it is my throw out bearing and clutch. witch is possible. i am in dire need of help. this is our only means of transpertation. and my mother is blind. PLEASE PLEASE PLEASE HELP!!!!