Is this something I need to do ?

If so, how and what should I use ?

Noticed some surface staining when doiung my SL55 Y pipe upgrade. Old carb cars I used to buy a spray can to squirt down, but not sure if it is safe to do this or what to use these days.

Also, how can I open the throttle with the engine running and squirt down the intake anyway ??? Damn drive by wire ! Give me a throttle cable any day.