"What we have is a phenomenon that is not explained by the calculated mass of the universe."
Vague statement. What we have are two phenomena, one which is not explained by the observed mass in galaxies or in clusters, and one not explained by the present (and currently only serious) model of the universe. Feel free to propose alternative models for the universe... but make sure that they fit the current observations *at least* as well as that model and fails to break the Solar System. That is hard to do.
"As a filler we have titled it "Dark Matter" and "Dark Energy" and given it a mathematical correction to the calculations."
True, with the correction above.
"The mass issue is fixed if we realize that the size of the universe is larger than the visible horizon."
No it isn't. That will do precisely nothing for the rotation curves of galaxies and will also basically do nothing for the cosmological problem either. Vague hand-waving and appeals to Mach's principle don't hold without a concrete model. Provide that model and people may be convinced, but at the minute what you're suggesting is startlingly acausal and, as a result, unacceptable.
"Meaning it is bigger than we can see."
Very true. No-one thinks that the entire universe is the observed universe.
"With that we can assume that we can only see 13% of the whole universe and that the reset of it is too far away to see. Now, run those numbers through the formula to calculate the expansion rate of the universe and you get some great results!"
Nope, you get precisely the same results that we currently get, because while it may startle you, that's what we currently do -- effectively. Thanks to causality, matter outside of our horizon cannot have an effect on us. Basically, something which is far enough away from us that light cannot have made the distance cannot possibly have influenced us. That, or you have to propose a new theory of gravity -- good luck with that one. It's a common game in cosmology, and one which precious few people since Einstein have had any luck at.
"The energy issue disappears when you realize that the closer an object is to a gravity well the slower time moves."
No it doesn't. Do you think that we're using non-relativistic models of cosmology? Relativity is at the heart of your statement that gravity wells dilate time, and relativity is at the heart of cosmological models.
"Thus there is a large time differential between the edge of a given galaxy and intergalactic space. This time differential accounts for the perceived added gravity."
Now this is a much more interesting statement. Dig out Wiltshire's attempts to use time dilations between galactic clusters and voids to explain the dark energy problem, firmly in the context of general relativity. The fundamentals are not well-studied, but it is promising. However, it goes the opposite direction from your surmise -- it tends towards providing a dark energy rather than a dark matter. It does drive home the point though that it is vital to actually try and calculate something based on an idea, properly rooted in a concrete theory. The answers might be rather different from what you expected...