Could it be bad gas?

[w123love]

Hello all-

I'm considering going to the dark side and wetting my feet in petrol Mercedes.

During a test drive today in a W123 200 (M102), the car was very sluggish during initial acceleration. In first gear, with the accelerator pinned, the engine would struggle to accelerate, as if was starved of fuel. After a couple seconds of this struggling and slowly raising RPM's, it acted like a well performing engine, shifting through the gears and providing plenty of power with great acceleration.

Free-revving and idling was not a problem. The fuel in the car must be at least a year old.

Could this just be as simple as old fuel?