Two of my Volvo's went through an acceleration stutter with heavier acceleration, but would always run smooth out on the highway. New spark plugs fixed them both. Also both cars never threw a check engine light. Just a thought in case you might think its coming from the engine.

This summer I bought a cheaper splash shield from FCP Euro. I was disappointed with build quality and wished I'd bought the more expensive Volvo branded one.
Years back the URO one I bought was way better than the Professional Parts Sweden one I got this summer.