If you have trouble shooting approaches and doing stalls and steep turns at 1,500 + hours, than you haven't spent your time wisely...Aside from a couple maneuvers and a shut down, the ATP checkride is no different than anything you will experience on an IFR day...
I believe i logged a block of 3.1 flight hours on my ATP checkride, mostly because there are so many boxes to check off, but it was by far the easiest and stress free checkride i've ever taken, and it was single pilot with the fsdo.