"Past the middle" is well beyond 215 on my gauge and temp sensor. If your OBD2 readings are that far off of what an IR thermometer is reporting I'd be suspicious of your sensor. edit: I thought I read 15 off, not 5. 5 I believe, and is because you're measuring the outside of an aluminum neck, not water temp with your IR gun.
Then again, I've seen different behavior from a lot of these trucks in more ways than temp gauges, they're 25 years old and full of worn out and/or aftermarket parts, bad grounds, crusty connectors so I suppose it's getting harder to say with certainty how any of them will react with specificity.
But one thing reported over and over and over through the years on these vehicles that absolutely matches my direct personal experience with several of them (including D2s!) is what you responded to.