If your AVR is 4 years old it most likely is not HDMI 1.4. The great thing about the PS3 is its not really 1.4 either. If you connect the PS3 directly to the TV and run the setup again it should setup 3D then reconect it to your AVR, as long as you don,t run setup again it should work in 3D. The PS3 does't check for a 3D device every time it plays a 3D game or Blu Rays as all other players and SAT/Cable does.
Smart enough to know better, to old to care