Whats wrong with my OIL PRESSURE?

Thats strange. It is probably something to do with the A/F mixture and the tone of the engine or a small exhaust leak lke you said. As for the fluctuating oil pressure at idle the only thing that I can think of is your oil pump bearings but that is very highly unlikely. Unless your motor really is reving up and down then your oil pressure will move a little. Id check the wire that leads to the tach on the ignitor inside the distributer. If it is loose your tach will read incorrectly. I have had mine drag over 2k rpms behind because of a loose wire terminal.