I am currently dealing with an issue I have never ran across before and I need help.

Sometimes, when I go to start the truck it acts like a standard dying battery. The engine turns over slower than normal and after about 3 seconds starts to really slow down with the under dash clicking sounds. The second attempt generally is even worse and quickly progresses to the point where the dash goes out and the motor barely turns over. Sounds like a standard low power issues so far. But if I don't let go of the key, after a few seconds of barely turning over power comes back it spins up to normal and starts right up no problem except I have lost all radio settings as if I lost all power. This only works if I keep the key turned through the power loss. If I let off and try again it just repeats the slow turn over until I hold it there.

I say this happens sometimes because it is intermittent. Starting up after a short stop has been fine so far. Starting up after a few hours almost always causes it. But starting up after sitting overnight has only done it twice so far.

I have checked the batteries, good.
I have checked the wiring, good.
I have checked the ground, good.
I have had the starter tested, good.

This started about two months ago and is definitely getting worse over time.

Does anyone have an idea about what is going on here? I am stuck.