Q7 slight engine stutter
 

Brand new to Audi and the forum. I bought a used 2008 q7 with only 37k miles. I bought it a few weeks ago and the other day we had lots of rain. After driving for a few miles to the store and parking it for about an hour I realized it was hesitating when I accelerated? I then quickly got the check engine light and couldn't rev past 3500 rpms. After a bit I put it into sport mode then manual mode and then seemed to drive normal again???? The light came off after a day but now from time to time after a cold start I feel a hesitation for a bit so I just ease off the gas then proceed... It's fine after that initial hick up but just seems some thing isn't right. It may be unrelated... 2 weeks prior to that I got a low coolant message that only came on after a freezing cold start but went away and hasn't appeared since.... Just worried so I wanted to see if anyone had an idea what it could be.