Vauxhall Meriva running problems

My Son owns a Meriva Tech Line of which he is having trouble when driving under load. To try and explain in a little more detail the vehicle tends to 'hunt', for want of better terminology, during acceleration and under load. Especially up hills. It's feels likes it's misfiring, but I have a sneaky feeling its something else. Just not sure where to start? Once it starts to 'hunt' the symbol showing a car with skid marks comes on and will not go off until the ignition is switched off and everything resets itself. The Traction Control will not operate, nor will the light illuminate whilst the fault occurs. The acceleration is very poor, even going down through the gears, but will ease slightly once speed is gained and the road levels out. We have put the OBD reader on and no faults are showing. I am now at a bit of a loss and hoping one of you fellow Meriva owners may have an idea where to start?