So I have no idea what I’m doing really I’m learning as I go, had a bad coolant leak I was told, I replaced the lower hose, seemed to stop leaking.

Took it for a ride.

Gas tank was low, car was on a incline in a driveway, was parked like that for an hour or so, wouldn’t start.

Got it it down to a Slightly less sharp incline, it started eventually, and I thought maybe from it sitting and having not much gas, maybe moisture was at play, so I got some gas, that dry gas ****, and prayed that was it, because it’s never given me issues starting before.

Took it for a ride to see if the coolant would run out, I have no evidence of it leaking, but I feel like I’ve put enough in to fill the coolant reservoir, like probably enough to fill it, but I’m assuming because I replaced that hose it just has pockets of voids without it coolant it needs in there, and wants to take some for those.

But now it was whining, especially in lower gear and at lower speeds, about 43MPH and under it will whistle a bit, it sounds like a flute.
And changes “notes” on the “flute” when it was slowing down or speeding up, this seems like it happens more when idle or going from like a red light up to that 43 MPH mark.

It would shake a bit too, not too bad but you feel it. Enough to be concerning.

So I get an OBD and get a P0300 I believe. I have the “snapshot” or whatever if that would help.

So I figure to start at the spark plugs for the misfiring cylinder (the P0300) it didn’t give me the digit to know which one so I figured just take a peek at them all and the coils.

One of the spark plugs had debris in the chamber, and I was told it may need to be replaced.

So I start to think I’m making some progress.

I peek under the car and now towards the front under the car, I’d say under the drivers seat is a glob if an oil looking substance, so screw off the oil cap and there is this awful goopy, yellow white looking glop all over the cap and a little down inside the chamber.

I’ve been told it’s possible antifreeze is getting into my oil, it could be a seal? Or a timing cover? Or a head gasket?

Any advice would be greatly appreciated!

 

Everything you wrote points toward the same conclusion - a blown head gasket. That would explain the recurrent coolant leak, the misfires, etc.

Don't start buying coils or anything else. You have a few options at this point...

1) Old school - tear down the engine, remove the head, take it to a machine shop. They'll plane it down so it's flat again, then you can reassemble it with new gaskets. Not a job for a non-hardcore shadetree mechanic, IMHO.
2) Old school, version II - tear down the engine, remove the head, throw it away. Go to a junkyard (or maybe eBay) and buy an IDENTICAL head, and reassemble the engine. A little less daunting than #1 - probably cheaper, but subject to importing any issues that the donor car had due to the head.
3) Replace the engine (might end up being necessary if the coolant-soaked oil has caused bottom end damage in the engine). Of course, you're probably not going to know if this is the case until you do fix #1 or 2. It's a risk. Replacement engines can be relatively inexpensive, though installing and sorting them out isn't (if you DIY, it's a big job requiring some special equipment, like an engine hoist).
4) Try one of the many (!) "head gasket fixer" snake oil products. From reading a LOT of user reviews, it appears that some of them do work at least reasonably well. I'd never recommend this for a car you're planning to drive for another 50,000 miles, but it might be worth a shot. And if you DO go this way, start out by changing the oil with the cheapest dinosaur oil you can find, and see how it goes. If it DOES work, then drain and replace the oil with high-quality synthetic.
5) Sell the car. Might be a very reasonable alternative (though no one can tell since you didn't tell us the year, model or mileage). Of course, don't try to sell this to some poor single mom or dad who's trying to get a safe car to take Junior to daycare - put it on Craigslist as a "mechanic's special" and be honest about the problem. Someone dumb enough to take it on will be there with a (small) pile of cash.

 

Unless the oil is gray and watery I dont think you have a gasket problem.Some stuff can form under the cap when the car runs short distances in cold weather all the time and never heats up properly so the moisture can not evaporate and will gather under the gap mixed with oil fumes.

 

Use to have a 98 S70 T5 that was driven 6 miles one way at a time and then sit for days. During the winter the cap would sludge. However, if the OP suspect a head gasket problem try this test first. Can borrow the tube at Advance and the Fluid is available for purchase. You can leave the plastic expansion tank cap off during warm up before it gets too hot.
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Yes, you can get a thin coating of "milk shake" on the cap from not properly warming up the car, but the OP's description didn't sound like that, and all his symptoms sound ominously like a bad head gasket. The previous post should be helpful in determining whether that's the case or not. If it is, please refer to my previous post...

 

true, there should be other symptoms if the gasket is bad, ie oil or coolant consumption, rock hard upper radiator hose, sludge in coolant reservoir, odd (sweet) smell to exhaust, CEL due to misfires, loss of power...

 

Yep, the misfires and the debris in a cylinder are all pretty ominous. The "whistling" might be steam escaping from the crankcase (it's going to overwhelm the PCV system).

FWIW, I'm still hoping someone with a bad head gasket will give one of the "head gasket fix in a can" products a try - not what I'd do for a car I plan on keeping a long time, but a reasonable solution (or attempted solution...) on a high-mileage, low-value vehicle that's not worth the cost of a new / rebuilt head.