Hey,
I have won on Emporor several times on domination, but Its always been duel / tiny maps and having 6-7 nations on a single continent.

Now I'm playing Tiny map with 3 civs and I can't keep up with the explosive settlers they produce.
I keep my Tech at 80% and keep building Settlers but still trying to keep a wonder economy which I can horde most of the wonders... Stone henge, walls, oracle and pyramids, then I relax down on that city and decide whats best in the cirumstances. But whenever I look over at my friendly neighbours... they have 8-10 settled cities where I only have 4. Any more growth and I have to take my tech % down...

How can they expand so much... without killing their economy.
Any tips?

I was thinking of going for a leader with Financial/Imperialistic.. but I found out it doesnt exist.
Shame.

Build settlers instead of wonders?

Building wonders is ok, as long as you do it for a purpose, and not just build them for the "ooooh, shiny!" effect.

Victoria is imperialistic/financial.

Rex (rapid early expansion) until your research slider isn't in deficit at 60%, and if you have enough to raise it to 70%, settle more land.

A slow start is typical for the Wonder Economy. WE is all about storing up potential, to boom later. So don't worry, it takes a bit of getting used to, different pace to most other approaches. Moving from 5-6 opponents to 2 also changes the dynamic hugely.

As Matthew says, no need to stay at 80%--that's generally a signal you're not settling enough land. What I do is flash out 2 Settlers and 2 Workers once the capital has hit happy cap, and then delegate the empire building to those two new cities. One needs to be food rich to supply more Settlers and Workers, the other production rich to buld your defense forces.

This late settling means you're going to be well behind the AI in city numbers early on. Not to worry, it's city quality which counts at this stage, not sheer numbers. You leverage the quality later to bring yourself level, and your WE will then surge ahead.

I prefer to gather intel while developing the WE advantages, and not make the main strategic decision until I've met all civs--usually after Caravels for me, much earlier for you on Pangea of course.

For WE, you should be better off going with an Industrial or Philosophical leader. Try Huyana [Ind + Fin], although imo Fin doesn't shine in a WE. Elizabeth iirc is Philo + Fin, probably a bit better--WE sits better with Philo due to the GP focus.

I haven't tried Imperialistic leaders yet, but it could suit if you get the GWall. Imp helps the early settling weakness, and the GWall will add to the GGeneral count if you get attacked.

Maybe not with 2 opponents, but generally in Monarch WE, you have to let some wonders go. Early intel is a big help for this decision--eg lot of psychos around means Chicken Pizza and SoZ should move up the list. WE is tough to survive early on in a rough neighborhood, to the extent that it's probably a poor choice of approach unless you're Protective [eg Qin or SBull].