Could be coil pack, in my experience a failing one will break down, (or at least be noticed more) when its under load, which at 3500 revs it will be. It will also be more noticable when it (the coil) gets hot.
As for loosing oil pressure when its hot, dont know tbh mate, sorry! Cant see how they would be related, unless the viscosity of the oil is to low so it goes p155 thin when its hot and bringing the light on? Not sure tbh but just a thought.