i recently bought a 1977 datsun 280z and everything checked out fine. ran it perfectly for about 3 days. i hopped on the free way for about 30 miles and just as i exited my cars rpm dropped to about 500 and stalled. before that i checked all hoses and replaced faulty ones. i am not sure what it could be?? can anyone point me in the right direction?

I get the feeling that you're not a motor-head. Does the engine turn over? Is the electrical system intact (do the headlights work)? You haven't given any info on what you've tried so far, to diagnose the problem.

Sounds like 3 days of driving clogged up your fuel somewhere, try a new filter up front. You should put one between the tank and the the fuel pump too, Z Car Tech Tips Fram G3 Filter Installation

sometimes previous owners do not secure the battery and it slides. When this happens the +pos terminal will short to the inner fender area.

Usually if the car just dies and the tach drops instantly, it is a transistor failure in the ignition system..typically caused by heat. Once it cools the car will run again until it heats again

As mentioned above, rust from an old gas tank can clog the fuel lines.