VDDCORE & ENVREG connection when it is not used
It looks like the PIC18F65J90 is a part of the PIC18F85J90 family.

In section 23.3 On-Chip Voltage Regulator of the datasheet:


  All of the PIC18F85J90 family devices power their core
  digital logic at a nominal 2.5V. For designs that are
  required to operate at a higher typical voltage, such as
  3.3V, all devices in the PIC18F85J90 family incorporate
  an on-chip regulator that allows the device to run its
  core logic from VDD.


So that says the core digital logic modules need 2.5V.


  The regulator is controlled by the ENVREG pin. Tying
  VDD to the pin enables the regulator, which in turn, provides
  power to the core from the other VDD pins. When
  the regulator is enabled, a low-ESR filter capacitor
  must be connected to the VDDCORE/VCAP pin
  (Figure 23-2). This helps to maintain the stability of the
  regulator. The recommended value for the filter capacitor
  is provided in Section 26.3 “DC Characteristics:
  PIC18F84J90 Family (Industrial)”.If ENVREG is tied to VSS, the regulator is disabled. In
  this case, separate power for the core logic at a nominal
  2.5V must be supplied to the device on the
  VDDCORE/VCAP pin to run the I/O pins at higher voltage
  levels, typically 3.3V. Alternatively, the VDDCORE/VCAP
  and VDD pins can be tied together to operate at a lower
  nominal voltage. Refer to Figure 23-2 for possible
  configurations.


Figure 23-2 shows your three options to supply the digital logic modules with 2.5V.



Since you are supplying 3.3V, I would go with the first option and let the internal regulator provide the 2.5V for you. Tie ENVREG to 3.3V and use the appropriate Vcap.