One other thing to check other than ignition. Did you confirm that the exhaust isn't restricted? Something about idling well but slowly dying after the revs (and air flow/backpressure) are increased make me think plugged exhaust.
I don't know why the engine would be boiling hot after a minute of driving if it idles great indefinitely if the exhaust is clear. Even with the spark all the way up it shouldn't get that hot that fast. Based on everything else the engine sounds pretty healthy
