My Nissan Primera jerks when accelerating and turning slightly right. Problem when overtaking (UK).?

Mostly this is a problem on the motorways, I have to pull out into the overtaking lane first and then accelerate. If I accelerate and turn slightly to the right the car will jerk and loose power until I straighten up and release the accelerator. Sharp turns to the right however don't seem to cause a problem, only seems to happen when turning onto motorways or overtaking. I took the car to a garage and they did a computer test that cost me �50 but they didn't find anything wrong with the car. The only thing I could think of was maybe some flue or electrics pipe or something was getting squashed by stress as I know the engine can move slightly, but can't really see anything in the engine that looks like it could get squashed but I'm no engineer.