Add cheap Chinese impellers and 1/4 NPT plugs to your 'do not buy' list.  Why on the 1/4" NPT plugs from Amazon - they are too small, guess they save material across a few thousand of them, ok rant over on that one much easier to find than a bad harness.  Story for you - I was checking on some wiring harness' at a manufacturing facility stateside which made wiring looms, all the workers were Chinese women and holy s**t they were fast!  No way ever I could get that fast and accurate as they were, it was impressive to watch.

An additional few items to check:  1.  check to see if there is a vacuum leak at the intake manifold, any old rubber plugs and the potential of a leaking intake gasket.  To check, spray some starting fluid around the gasketed joints and if the idle picks up, presto.  2.  when the distributor cap is off, check that the rotor is firmly attached and there is no slop in the rotor (rotational play) as the distributor gear could be worn (checking timing will show scatter at idle).  3. and start with making sure base timing is correct (~8 deg BTDC).

I wish the OEM GPS puck was that cheap.....

Sorry, I'm no help.   

2 hours ago, Slayer said:

I tried several zip codes in my region and received the same message.

 

2 hours ago, Hemmy said:

Tommy's probably wasn't your local dealer which is why you are locating one.

Don't shoot the messenger, was just saying if I put my state in I got nothing.   I put my ZIP in and it worked.  I checked other ZIPs and got dealers.   Whether or not Tommy's was a dealer in those ZIPs, I have no idea.    

I have noticed that my navionics will almost always glitch out when I switch between it and other screens (ballast/lights/stereo/etc).  If I really want it to work, I cycle power, then go to the nav screen as soon as it fires up.  It will work flawlessly until I switch off of it.  Many of us have switched to using our phones/ipads and navionics app vs depending on the screens to function. If you are close to your dealer, perhaps let them dig into it.  It could be a software or firmware issue.  It’s not an often utilized feature so I could see it being a low priority for the Malibu/viper/medallion programmers.  I have a brand new oem screen on mine too.  I bought the navionics to decrease the pain of buying a new screen, at least id be upgrading its capability in the process - instead just got more doubt over the quality of oem stuff that is not returnable 🤣.