Regardless if you think you "fixed all vacuum leaks weeks before I did the LIM gasket and didn't change", you didn't. Mine pegs the gauge at 3/4+ throttle, if yours does not, there is a leak somewhere. You prolly just got it fixed once you put everything back together.
I did fix the vacuum leaks. I tested and tested again for leaks and everything was sound. Just because yours maxes out at 3/4 throttle doesn't mean mine does. My car has 200k.