Pull unused analog pins to gnd to help minimize noise?

Another thing to add - E.getAnalogVRef() is just another ADC reading internally, so even though you're taking a bunch of readings for the temp, you'll still have the jitter caused by changes in the values from that.

As you're not expecting that to change much, you could just keep some kind of running average of it:

var vRef = E.getAnalogVRef();
//...
   vRef = vRef*0.95 + E.getAnalogVRef()*0.05;
    var vOut = vRef * E.sum(view)/(view.length*65536);

You could also experiment with just using a constant value instead, like 3.3.