Not so sure about getting a 2014 I have had the same exact issue with a 2013 and a friend if mine with a 2015 I have 150k miles on it though. No check engine light no codes changed all kinds of parts. Dealer suggested continue driving until the check engine light comes on. I hate that misfire feeling though and driving on pins and needles thinking it will just die. Why Chevy hasn't done some kind of fix or recall just sucks.I was surprissed to read they offered you $4,000 !!!
Others on here have been offered some small amounts. (I think at most 2000?)..
But you said- its at 100,000.
You bought it used.. so you wouldnt 'lose' alot like if you had bought new (you still owe on the vehicle?)
I just looked up the trade in Value for an LTZ in my area and its about $14,000 (have they made a trade in offer?)
If I was in your situation-
I would consider trading it in... and using the $4000.
And either finding a leftover 2013...
OR getting a 2014..... I would consider at most a 2LT...
But most likely a 1LT... to keep cost low.
Youd have a new- 0 miles car....
and the rest-- pay off in a few yrs.