Well the 542 is a high resistance or open in the fuel pump circuit. If that is occuring then the engine will not be running.
The 587 is a lack of communication between the PCM and the VCRM. This should have been corrected by the replacing the VCRM. But again that will NOT cause it to be lean.
So we get back to the engine inputs.
That engine is not known for vacuum leaks. However, there are a couple of spots at the throttle body when the PCV system connects to the throttle body.
It is possible that smoking the system (which puts pressure on the interior of the induction system, exactly the opposite of how the engine runs) will not show a vacuum leak, and that is about the only place that I would be looking for a vacuum leak. I would also look at the pcv valve itself. If it is old and stuck open, then it is possible that it is causing false air.
The 181 is XXXXX XXXXXmit reached, lean bank one. It is possible that you are lean on both bakns, but that the limit has not been reached on bank 2. The bank 2 code will not trip until the limit has hit that limit.
You mention that you are at +25% short fuel trim. Is that on both banks or only on one?
Any vacuum leak, will also effect both banks.
Again, what is the age and condition of the o2 sensors?
How well are they switching when they are working?