2012 535I XDrive with M package slipping upon acceleration in lower gears

[gtandy6]

Hi. I recently purchased my first BMW 2012 535i Xdrive with M package with only 50k miles. I recently noticed that upon acceleration, I feel a repetitive slipping like wheels are hitting water/ice, but pavement is dry. I notice slip this in all modes (comfort, sport) and mostly in 2nd/3rd/4th. When I stop accellerating, issue goes away. I've tried adding techron to several gas refills and higher octane. No engine codes. Some additional background: Previous original owner used 87 octane and car sat in garage over Winter months for up to 5 months when they vacationed in South. Also, I noticed car shifts a little rough, especially when colder. Any thoughts ? I'm prepared to take to dealer, but I would like some preliminary thoughts on potential issue. Thanks Greg

[White94RX]

It's pretty hard to diagnose a driveability concern over the internet. Taking it to a dealership, or a reputable independent shop that specializes in BMW's would probably be your best course of action.