If you suspect a bad injector on cyl 6, try swapping it with another cyl to see if the problem follows.
A misfire like this can be a symptom of coolant ingestion. I know you said you just did the UIM / LIM stuff...are you absolutely certain that every
bolt was torqued down properly? Did you install the TB gasket (it'* been forgotten by more than one of us
)? Is your coolant level in the overflow now steady?