2018 AB LWB 5.0 SC. On a cold start in the high idle phase, my revs flutter very slightly up and down. Is this normal? After less than a minute when the vehicle goes to low idle the revs stabilize. What could be causing this? I’ve had an induction service done at the dealer including cleaning out the throttle body already but no change. Could it be bad fuel? I just bought the car used so l’m still using the gas it came with from the dealer. I’ve filled up with 93 gas and added a bottle of bk44 cleaner. No change yet. Any ideas? Thanks.