Sorry for the late response but I was looking around and came across your thread. I have been using the Rev-X for about a month and a half and I definitely notice a big difference when I first start my truck in the morning. It's much smoother and doesn't have that rough idle except for just a few seconds. However, the weather hasn't gotten cold yet so I guess the real test will be this winter. It's expensive, about $70 per treatment. For what its worth at this point I will add it again at my next oil change. There are some videos on YouTube with people doing before and after cold starts, check em out.
I was experiencing very poor performance before the engine reached normal operating temperature (stumbling, missing, jerking, etc); from what I have read, I seem to have had the same symptoms as what is referred to as "stiction" in regards to the injectors. I have 170K miles on the truck, I put in two bottles of the Rev X after an oil change and now the truck runs great. I was very skeptical at first, regarding how I could fix this problem by simply adding something to the oil, but I have been very pleased with the results. I don't claim to be a chemical engineer or even fully understand what this stuff does, but I have no regrets paying the $70 for it.