It would get down to 135 driving 70+ on the highway. But not any lower

Meanwhile, engine temps stable and sort of bounce between 194 and 199,

 

Maybe just a glitch?
Can you reset/update the ultraguage to factory specs?

 

I've been considering covering my intake tube with something like this to reduce the absorbed heat it gets from the exhaust manifold:

Heatshield Products 274308 Thermaflect Sleeve 4" ID x 3' Heat Shield Sleeve

Heatshield Products 274308 Thermaflect Sleeve 4" ID x 3' Heat Shield Sleeve

And wrapping the lower half of the air box in this:

Second Skin Thermal Block - Automotive Heat Shield

Second Skin Thermal Block - Automotive Heat Shield

 

I frequently use HVAC aluminum foil tape available at big box stores, you might want to try that for a test to see if you get the results you want.

 

I think at lower throttle settings the intake air gains a fair amount of heat from the engine by the time it gets to the sensor. When I first got my UG I expected the inlet air temp to be a good indication of ambient air temp but it isn’t.

 

I was thinking the same thing but wrap the intake tube with exhaust header heat wrap.