Was the sensor isolated from the duct work? (to rule out conduction of the hot pipes to the sensor?)

I'm surprised the air at the LH/RH intakes was any different than ambient, esp, if the probes were outside of the engine bay...must have some conduction ie you measured the pipe temp not the air inside (or some of each).

I'd guess that the IAT sensor (air temp in the inlet manifold) should be within 20 degrees F of ambient. This sensor should be insulated from the manifold by design.