Hahaha...yeah, well this one time...I just mentioned the word ethanol and my car went in to limp mode!
Obviously just kidding but...
A car running high percentages of E85 can have issues if the injector temps on certain revs of injectors gets too high....it can melt the internal filter.
That said...do your homework...some good info in this thread and some not so much.
To the OP...shopping around for a dealer that would work on your car with a Cobb tune still installed? Gotta question that judgement call...why didn't you simply remove it as opposed to taking the risk of having your car flagged?
Full disclosure.....I run 100% E85 and have done a crap ton of reading/work on it...and literally know this fuel system inside and out.