Yeah my VX has all of the symptoms now, idle low then high then low then wont idle, so I ordered the Fuel Pressure Regulator today from St Charles Isuzu and will be putting it on ASAP, so let me know how to get this from you, thank.
When you get the FPR from Merlin, marvel at the GM part number on the packaging...then, if you would, post a pic of the packaging with the legible part #. I'd like to do a little checking around for cross referencing...