so I've been having issues with too much interference and took the P3 to  open area with a lot of soccer fields.  Power lines a quarter mile away and thought I was far enough away from residences.  There was one home within a thousand feet of me and that's it.  I took off and things seemed fine....then started getting the "interference", "rc signal lost", rth was then triggered and it went vertical to 300m before then trying to land.  I have not had a single flight yet where I don't get multiple warnings so pretty frustrated at this point.

Guess I'll reinstall the app and relink the remote etc.....any other advice would be appreciated?

I did a test where i intentionally flew over and then beyond very large power lines to see what interference i might get and my P3A flew perfectly to about a mile with the signal going directly through the array of high-tension cables;  when i lost contact and RTH was initiated.  So, power lines offer little interference.  There is one very large home that i tried to fly over, and every time i tried, I lost contact and my bird came home.  I tried several times, once from only a short distance away, and it happened again.  Something in that huge home blocks my signal.  
I would guess, if this happens often to you, it is internal to your P3 either soft or hardware.  I am sure others here will offer more in-depth advice.  

To reinstall the app and relink the remote etc won't make any differenct to the interference your Phantom detects.
That's a feature of your environment and not something you can change except to fly somewhere else.
You also need to adjust your RTh height to something more appropriate.