The brief hiccup when the motor reaches operating temperature is caused by the computer switching from open loop emission control (used while the motor is cold) to closed loop emission control (used after the motor has warmed up). This is perfectly normal.
The clearances between the sensor and the triggering mechanism are very critical. On some engines, due to variations in manufacturing tolerances; those clearances may be larger than the design specifications. And if that was the situation in your motor; the sensor you installed would produce a weak signal, because it wasn't extending far enough into the motor. The solution would either be to use a different brand of crankshaft position sensor (Standard Motor Products claims that their sensors are better engineered and work more consistently than other brands), or to remove some material from either the sensor mounting flange, or from the engine's sensor mounting surface. It would be ideal if a measurement could be made of how much distance there now is between the sensor tip and the trigger; so it would then be known how much further the sensor could safely be moved inward.
The code you have been getting only refers to the crankshaft position sensor efficiency; so there is no reason to also replace the camshaft position sensor.