Now that I've been alerted that something is not right, I've given closer attention to the car's behavior on acceleration. When cold and first starting up and flooring the accelerator, the car has great acceleration. At about 2500 rpm, there is a surge of acceleration which must be the turbo coming on. The car has noticeable torque and easily speeds up and shifts to a higher gear at about 3600 rpm. Upon repeated acceleration, there is no noticeable boost but the car continues to slowly acceleration with rpms reaching 4200 before downshifting. This is the situation that seems to occur when I was driving uphill to Tahoe and other times. The car doesn't feel like it has much torque and struggles when the load is increased.

Is this a sign that there is some problem with the turbo no turning on properly? What are possible causes of this?