Enough of you know your way around anything with wheels that I might be able to get a solid lead from you on this one.

Here's the deal:

For a while, the car had occasionally smelled like coolant outside, after driving it a bunch. I didn't recognize the smell and didn't notice any issues with the car. End of September the A/C started becoming intermittent. One day we notice the temp gauge is about to hit red. I pull over as it's hitting red, pop the hood, and walk to go get some coolant. we keep driving after the engine cools down, go pick up a new radiator cap and, once the air bubbles have a chance to get out of the system, things are better. AC seems to works regularly, etc.

Only issue is that there's a smell of coolant in the car soon there after. I figure out the water pump's cracked so my buddy & I replace it. Coolant smell goes away in the cabin, but (since now it's later in the year) the heater works intermittently. So I replace the thermostat. Because of where it is, I've gotta unbolt it & re-seat it the next day as it was leaking from improper seating. I go to drive it to work and it starts overheating after maybe 10 minutes of driving. after limping it to a safeway & adding more coolant, striking off, and limping back again, I realize I knocked the radiator return hose off. I reconnect drive off again before having to limp back. Just as the temp gauge hits red I turn the car off, crack the radiator cap and let all the air that was blocking the system escape.

After more coolant, the car runs at temp just fine. I don't get a coolant smell in the cabin, and I'm only getting a faint smell of coolant in the engine compartment which I assume is all the coolant the blew around the compartment just burning off. Still no heat though.

After a while, I start to notice a faint smell of coolant after driving and getting out of the car, but it doesn't seem to be coming from the engine compartment. I smell it more around the mid area of the car. Still no heat.

I added a little more coolant to the system this morning because it looked low. On the way to work this morning, I warmed the car up in the garage for 15 mins, drove to work and on the on-ramp to 470, the revs were a touch high and the temp was 5/6 the way to red. As soon as I got up to speed, the temp dropped right back down to operating temp.

I can't see any coolant leaking from the thermostat or water pump that I replaced, or anywhere else in the compartment, and I can't smell a lot of coolant burning up anywhere like I could before. However, it seems like I've got a leak somewhere. I still have no heat either.

Any ideas on what/where to check next?

Oh, the car's a '99 Mustang if that bears any relevance. Thanks for reading