my 2006 chrysler 300 V6/3.5L suddenly accelerates sluggish ( sometimes) and once in a while shuts-off while making a slow turn...also car vibrates a lot while in idle and a/c turned on....running on idle on 600rpm..after car shuts-off while slowly turning problem disappears for some days...then returns with vibrating etc....tried fuel injector cleaner with no success..what's wrong? anybody with any ideas? thanks