How to get the temperature just right?

[Jazzper]

We are only using an UTH, with a dial controller on it. Which was recommended by our local reptile store.

The temperature of the substrate is irrelevant. You want to use your thermometers to measure ambient temps while using your temp gun to measure surface temps. And by surface I mean the enclosure surface, not the substrate. Snakes can and will burrow to the surface, so that's what number is important.

It sounds like your heat sources aren't regulated by thermostat?? If this is true you need one ASAP and should unplug your UTH.

And also, how are you heating the enclosure?
Your temps all need to come down a bit too.