I prefer the chevron techron injector cleaner. I'll give you the story of my idle nightmare. When I first got my car it idled horrible way to low almost killed the engine everytime at stop lights and it would shake the car violently. I didn't know anything about cars back then, so I took it in for an engine diag and they told me I needed an oxygen sensor which was a bunch of crap. Anyway I changed that with no change. I got a tune up done, and that helped, but still no real change. Then my I.a.c. valve was changed and that did that helped the most, then I prolly ran 30 different kinds of fuel injector cleaner in a 2 month span and that basically took care of it. Recently I got new battery clamps and that brought the idle back up a little. Now it's just about perfect, but it will be higher or lower according to engine temp, which is normal, but also tells me I have a problem with my coolant temp sensor, because once in a while it will be perfect at normal operating temp and other times it will be a tad low or a tad high. Hopefully that gives you a few things to check out, but there is ways to test your sensors don't just get new one's, and don't take it to chain shops like firestone. Get a voltmeter and a haynes manual they will sometimes tell you how to test a sensor, all though sometimes you need a scope for things like o2 sensors and t.p.s. sensors. Sorry for the book.