I think you should go back to the scene of the crime-
-Let's review ... you ran out of gas:
*OK it could be gas tank crap but sooner or later it should clear out.
*You had the cap, rotor and plugs replaced but still it runs like crap.
*You have changed the O2 sensor but it won't take a load.
My guess is to double-check the cap, rotor and plugs that were replaced.
-Question: MBZ cap and rotor? Plugs ... what kind? What are they gapped to?
My 2 Cents