30k is more than enough miles on an already condemned timing gear. They often make a loud noise something like a rod knock before giving up completely. If the timing gear is at fault for the running condition you will probably see by taking off the distributor cap and with a wrench or socket on the crankshaft pulley rock the engine clockwise and counterclockwise enough to see the rotor responding. This is a test that you might do on a timing chain motor to test for a worn chain but given your poor running condition the timing gear center may be completely separated from the gear itself. It shouldn't take more than a few degrees of crank movement to see it in the rotor.