I have been noticing lately that my 2004 S60 AWD (150K) has been driving a bit heavy. It feels as if I have to really push the accelerator in order for it to move. It's not driving as smoothly. I am wondering if this is a sign that I need a tune-up or a transmission oil change. Any recommendations?

To the best of my knowledge the trans oil has not been changed since I bought it used with about 100K on it.

Thank you.