Ok, you've probably got two separate issues here.
Leaking - This tends to happen when the device isn't making a complete airtight seal somewhere. Make sure you've got the clear O rings placed properly in both your top and bottom cap (sometimes one falls out and you accidentally put it back on the wrong side), the black O ring at the top of the chimney, and check your device for dents that can affect an airtight seal. I'm guessing you've got two O rings in the top cap or on the base piece and don't have one on the other side. A good way to test your seal is to cover all four airholes with your fingers and try to suck air through the drip tip. If you don't feel a vaccuum, keep checking - there's an air leak somewhere.
Burnt Taste - You're getting dry hits, and once you've had a few, your cotton gets burnt and you'll taste it all the time until you change the cotton out. Dry hits come from not having your wicking dialed in correctly. Check out some lemo builds on youtube and see how they wick it. Fixing the leak issue above will help a little bit, but you'll want to wick it right, too.
I hope that helps. Moving up to a rebuildable
tank will get you a MUCH better vape once you've got your setup dialed in, but there's a bit of a learning curve at the beginning to figure out how to get them wicked and built right. Keep trying.