Troubleshooting a 120v load off a GFCI outlet
When I hear weird voltages and intermittent, I think LOOSE NEUTRAL.


The neutral bus in the panel that feeds the circuit your garage door is on is not securely attached to the utility company's neutral.

If you're lucky, the mistake is in a sub panel and easily fixed.
If not, it could be he main panel, though that is less likely because ground and neutrals are supposed to bond there.
It could also be behind the meter, or at the utility's transformer.

Go check some 'good outlets' that come from the same panel.  If you see voltages higher than 120, or really any odd voltages, shut off the main breaker, and fix the neutral.  A loose neutral causes voltages on each Hot to vary wildly depending on load, and can easily damage devices in your home.

With the meter pulled, I'd recommend you check all three lugs in the main panel, and in every sub-panel if you have them.  I've heard stories of "licensed" electrician forgetting to tighten down the lugs.  And once a service is live, nobody in their right mind is going to poke or prod at the service conductors in a panel.  So it'd be hard to notice.

While the mater is out, a utility person will be there anyway.  So ask him to check the utility's lugs too and check for a loose neutral on their side.

I'll also go on to note a couple mistakes in your original question that I'd like you to correct, or clarify.


  The other outlets after the garage door with the 88v have less than a volt on the neutral side but good 120v between ground as well.


On the neutral side.  What were you measuring?  From Neutral to what?
120v between ground.  Again, between ground and what?


  WP outlet


What's that.  Did you mean outdoor outlet with weather resistant cover?


  it is testing good 120v between ground and neutral.


That wouldn't be good.  That would be extremely bad.  There should be negligible voltage between ground and neutral.  Ideally none.  Certainly less than 1-2 and then only in a very large house.


  The other outlets after the garage door with the 88v have less than a volt on the neutral side but good 120v between ground as well.


Again.  Incomplete picture here.  When you give us a voltage, you need to say between what two points you were measuring.