Ignition Coils

I have an 09 Acadia SLT2 with 99,500 miles that I purchased 2 years ago when it has 55,000 miles on it. Since then I have had nothing but problems. 2 ignition coils have already been replaced and I have a 3rd going out now. Is there a reason for this or is this common? Also my power steering will only work if the engine is reved. Parking is a nightmare as its hard to steer when the vehicle is idling or moving slowly. A new pump was installed as well as other parts pertaining to the steering. I have always preferred GM but after this experience I will never buy a GM product again