Look up some of the guys on Importfanatix.com.
They have the lowdown on most of the dealers in the metro area.
Scrapin240, a member of this site (who hasn't posted in ages) was a fellow IFXer -he had a VX in Queens.
For basic mechanical work, I strongly suggest the Midas shop on the 1&9 in Jersey City. It is run by a man named Sam (Abubakr, I think), who is a smart and talented mechanic. He's taken care of me in the past (used to live in Hoboken) and I'm sure that he'll do you right.
You won't find too many Isuzu dealers that qualify as "good" around here. Just a few bright spots (like Merlin at St. Charles) in a relatively shady crowd.