I'm looking for the definitive uber calc book that stresses the fundamentals, then rapes you with the most outrageous problems imaginable.
Before I can make a recommendation, have you ever done a proof before?
Which are you more interested in: proving why something works/formula exists or taking the end result and applying it.
In general the former is much more difficult and is what you would experience in an undergraduate mathematics degree. The applied side of things, depending on difficulty, is what you'd experience in your typical undergraduate core engineering/science classes
Judging from your post, I think you're a little misguided in what a difficult math problem is.
Addition
1+1=2 Easy
1.27845927457245284572458728045720457245807245 +2.38402738402734028340937840273402374203 Still easy, but time consuming.
The way you phrased your question it seems that you're looking for a bunch of those time consuming problems - which aren't necessarily difficult, they are still stressing the same fundamental ideas, but maybe just take longer/few more steps/requires a couple tricks...but really nothing exciting/new.
Anyway, what I'm trying to get at is your typical calc book will just ask you to understand the basic workings of the formula. The harder questions will just guide you to some "thought exercises/slightly deeper properties of the formulas
A book based on proofs wouldn't really have the typical word problem/application problems. It'd have you understand the proof of the formula (or have you prove it yourself) and then from that basic idea...what else can we come up/imagine?
Bottom line - do you want to think deeply about simple things or apply simple things to increasingly complex scenarios?
My recommendation would be for Spivak Calculus 3rd edition