Unless you are unknowingly renting far below market value or can do something to dramatically increase rent (highly unlikely, and even if so, you have a huge gap to makeup $500+), I would get rid of the property as fast as I could. 

First It appears your gross monthly income went up dramaticly.

ARMs can vary dramatically.

The most dramatic rental rate change I had was one of my SFR in North Scottsdale that used to EASILY rent for $3,200 per month that was now struggling to get a Tenant to pay $1,800.Many people who couldn't afford to live in nicer houses, suddenly were able to. 

The chance of water heater failure begins to dramatically increase at age five.

If you are on hillsides where foundation walls, caissons, etc are needed, obviously the price jumps up dramatically.

However when searching for the book theye are two different editions with dramatically different prices.

Because we have added value by finding long term renters (all leases are 5-7 years), the value of the property has gone up dramatically.  

Paying off the car will dramatically reduce the monthly financial burden as well.  

My feeling is that when the market eventually does dip there will be a lot of investors ready to jump in which will stop the market from dropping to dramatically.