1995 Toyota 4Runner Clicking noise from engine

Check all of your plug wires, first thing. Be sure that they are all properly connected (Pushed all the way on). Next, try starting your truck in neutral, and reving your throttle at the throttle body (or gas pedal if you dont know where your throttle body is located). Only slightly rev your engine at first. Hold it at about 2 or 3000RPM and listen. If you still hear a clicking, or "knocking", that usually a good indicator that you are having some serious engine trouble. Either a loose wrist pin, Bent/broken piston rod or something otherwise internally. The next question is, if your losing that much oil, where is it going? If your burning it, you'll know. If it's leaking, well you should know that too. Find out where it's going. Also you will want to check both your coolant and your oil to see if one is mixing into the other at all. If so, you may have punctured your block (Thrown a rod) otherwise known as "Worst Case Scenario" Time for a new engine, or at least a re-manufactured block.
And finally, because it never hurts to check, try cleaning your fuel injectors w/an injector cleaning agent mixed into a full tank of gas. That would be cheap and easy, but you would need to allow nearly a full tank of gas through it before the injector cleaner will have done it's job. So be patient and listen to that engine. Good luck. BK. Please check out my 95 4runner idling question.