Toyota Repair: 92 previa stopped running, rattle sound, carborator

Question
My previa has been slipping it seems with a jerk like feeling for some time now, about 6 months. Now my wife drove it down our street and heard a knocking or rattle sound and then it stopped. We tried to jump start to no avail. It also has a small oil leak somewhere, could this cause it to shut down, or do you think it could be the timing chain or sparkplugs,wires, dist. cap or something else. What about the carborator not getting fuel. Thanks...Tim Also I have had the starter replaced about 8 months ago. The battery does crank,but won't turn over.

Answer
From what you're telling me I can't tell if the problem is the engine or the transmission, I'm assuming the engine won't start, does the engine turn over when attempting to start it but not fire up or does the engine not turn over at all, have you checked the oil level of the engine?