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" ------ Dedicated Home Theater, Mitsubishi HC7900DW Projector, 110" 16:9 Jamestown screen with variable power masking for CIW 2.50:1 to 16:9, Marantz 7009 with 7.1.4 Atmos with Ohm mains,3 DIY Subs (2 15" (1 ported, 1 sealed and a 12" 4th order bandpass), 1 DIY butt kicker, Custom Built HTPC, 10TB DroboFS NAS