Surging can be due to lack of fuel, or less likely too much.
My car surged up slight inclines etc due to shit light throttle tune, it was running too lean.
So yeah, check fuel pressure from pump, fuel reg, and or airflow meter.
Rear tyres worn more than the fronts can also cause the attessa to try and feed power to front wheels. If there is a diameter different it can also cause that surging feeling.