I'm going to have to agree with most of the experts here. None of those are combos, and in fact, many anti-synergize.
Margrave/Fool's Gold -- Margrave is a bomb, but I'd be somewhat wary of using it on a Fool's Gold board depending on what else is in the Kingdom. Allowing your opponent to draw a card before going down to 3 is dangerous. If you're playing a Margrave engine and allowing them to do that multiple times it's even worse; you're significantly improving their chances of lining up THEIR Fool's Golds in the same hand!
Ill Gotten Gains/Stables; Treasure Trove/Stables -- Add me to the chorus. Stables does NOT want more treasure! The point of Stables is that you need to do LESS trashing. It's certainly not that you want to do no trashing, and definitely not that you want to add treasure. Stables starts to shine when you can play multiples per turn. If you load up on treasure, you will definitely not be able to string Stables together. If you're just playing one and discarding a copper or IGG, then, well...you're playing Moat/BM. Seriously. Ick.
I'd like to add one small story about trashing and engines. I had an IRL game recently that included Embassy, Chapel, Bridge, Port. I thought to myself: If I'm going to build a double-Province Port/Embassy/single-Bridge engine, can I get a jump on my opponents by skipping trashing and buying components faster, using Embassy's incredible sifting power and the lightning acquisition speed of cheap, plentiful ports with Bridge buys. One play of Embassy skips the Estates. Another play skips half your copper. Who needs trashing? Yeah, well, turns out, even THAT needs even some trashing; it's all about reliability. The player who trashed everything won on single Province buys (and free silvers, of course) before I could get doubles going. So no, don't ever, EVER clog up your deck with extra coppers unless you're playing some sort of slog or Gardens rush.
I recently played with some young beginners who tried to tell me how great a Beggar/Moneylender combo was. The fact that I had to actually work to convince them otherwise was truly astounding.
Journeyman/Fool's Gold -- And what are you going to name? Copper? Here's your handful of Estates. Oh, you're trashing those? In that case, trash the coppers as well and see what else is in the Kingdom before you buy $5 Smithies. Journeyman is terminal and doesn't have +buy, which means that Fool's Gold doesn't really like it.
The Fool's Gold strategy article on the Wiki is actually pretty good. It could probably use some updating, but that's the best place to start when you're looking for strategy advice and combos. Posting a poll here if you haven't done your homework is just asking for a pile-on.