There has been a lot of misinformation about the details of foxtrot timing posted here in other threads the past, but that probably isn't what you really need to know.
The challenge is that even when you know what timing you want to do, it is still often quite hard to do it.
The answer is to be careful not to rise too high and get stuck. If you rise too high, you will lower too fast, and you will land a step before you intended to. Then, because you are moving too fast, you will rise too early for the next measure, and continue on up until you are too high again.
Dancing a good foxtrot is a combination of building strong feet that can carry your body through slow, sustained movements. But even more importantly, learning to aim your movements within the scope of what your feet can carry - and what your partner's can carry, which may be more of a limiting factor. It is supposed to look like an effortless floating dance - don't let it become bombastic.