I know guys who use it and they like it. I've never used it myself nor do I plan on using it.
88-90 isn't too hot but it will produce only males.
In order to help you with the other question I need to know more about your set up.

1. what type of incubator?
2. how are the eggs set up? in deli cups? shoe box bins?
3. are the breeders proven?

Just want to isolate the issue as much as possible.