I have recently replaced front shocks for my 2005 Nissan Altima. After that I started to feel vibration when I drive. Thinking it was tires issue, which they were old already, I replaced them with the balance and alignment. The vibration reduced a little bit but it's still there. It's not vibrating on idle, only when pressing the gas pedal on the road, when I remove my foot from the gas the vibration reduces significantly.
What could be the cause? Is it an engine issue or something to do with the body?
One more thing, my friend's 2007 VW Beetle needs a battery replacement, does he need to take the vehicle to the dealer for some computer reprogramming after the battery replaced?
Thanks a lot for the help you offer.