Selling cashflow property to grow portfolio?

[Michael Kaminski]

I've tried to build some spreadsheets but can't seem to make any sense of a clear path but maybe that's data enough to not take action.

I bought a duplex 7 years ago for 188k and now I'm guessing it would sell for close to 500k. It is assessed at 535k and there aren't many multifamily properties to compare to. The duplex is a 2 bedroom 1 bath on each side and rent has gone up dramatically. One side rents for 1k (good long term tenants slow 3-5% rent increases) and the other side rents for 1.5k (turn over allowed for aggressive price increases). After mortgage, taxes, insurance, and other costs this property cashflows ~1400/month. I owe 130k on the current mortgage. 
I could 1031 but when I'm trying to find a better property in my area, Boise Idaho, nothing seems to come close to the benefits I already have with this property. I absolutely don't have a perfect picture of what better means but in my mind it should at least break even?

I think after closing and realtor fees I would have more than 300k to invest. Buy 2 properties and just wait for rents to come up? If the new properties broke even at least I've doubled the property appreciation that can happen.

Am I thinking about this from the wrong direction? Any suggestions, doing nothing would be a valid response.