The first thing to check is the connector on the rear of the instrument panel cluster (IPC). Make sure it is tight, not corroded, and has no damage. If that is good, then I want you to check two fuses in the under-hood fuse box. I don't think they are bad; I need you to simply make sure they are tight and there is nothing causing a bad contact. Pull the fuse and inspect where it goes into the box.
You mentioned a possible ground issue. That is a possibility as well. If you look at the attached pics below, I included the wiring schematic for the instrument panel. I highlighted the fuses to check, the wires related to the ground. Note, the ground location is behind the left kick panel. That is where your left foot would rest while driving. Also, there is a splice pack that will be attached to the harness going to the IPC. It should be close to the firewall under the dash and the wires will be black with a white tracer. If there is a ground issue, that is where I would suspect it could be. Something may have corroded at the splice causing issues. The last pic below shows the ground.
If you look at the last picture, I highlighted the two fuses I would like you to check.
Here are two links you may find helpful when testing / inspecting:
Let me know what you find or if you have other questions.
See pics below. Note: The schematic was two pages in length. I had to cut each one in half to make them readable for you. I did overlap them for you so you can follow from one to the next.
Images (Click to enlarge)
Tuesday, October 12th, 2021 AT 6:49 PM