99 civic w/ slipping problems. related to intake?

Hey, I appreciate any help you can give. I've got a 99 Civic AT and after getting what I think is some questionable fuel, have started to experience a feeling of "slipping" when I go into 3rd. It feels like some gear is "whirring" trying to find itself. it also runs pretty rough. I have had regular work on it, tuneups, etc. I even added some Lucas Oil transmission fix to my tranny fluid (which is pink and not burnt). I haven't had my intake cleaned out in a while. could the two be related? Thanks again.