Oh, I so feel your pain. DS woke anywhere from 8 to 12 times per night for the first 11 months of his life. Then we "progressed" to about half that. It was torture. At 5, he is still not a great sleeper.
The only thing that ever seemed to work a little for us was just to physically wear him out. Lots of walking, playing, running. Maybe try upping his actual physical activity and see if it burns some of that excess energy he is drawing from.
I am certainly no expert, but I sure can commiserate!
SAHM to Pete and Repeat my "Irish Twins" - DD 12/06 and DS 11/07
Never argue with an idiot. He'll bring you down to his level, then beat you with experience.