i have found i definitely do better when i lay off coffee for a week. i have had the worst habit of coffee imaginable - spending years sometimes drinking nothing but coffee day and night. i am down to half a pot a day from two pots plus only a couple of years ago. i dont drink coffee when i am fasting either.
about the flush: i find that if i dont stop the coffee for a week or so before, i have less production and some incomfortableness in the liver area lasting for weeks sometimes. that happened time before last when i only quit a couple of days before. i continued off coffee for another week and did a flush and felt great. its getting me through the holiday feeding frenzy!