sounds like two different things.
1. You are throwing an O2 code for being catless, when your CEL comes on it automatically disengages cruise control
2. You have a wheel out of balance. Not by much since it is within a specific speed range. For example, mine happens around 65-75mph which makes the interstate suck.


and for the future, you will need a retune because going full throttle in 4th or 5th gear may cause creep from the lack of backpressure (going to a 3" and removing the cat will do that)