Well I'm definitely infamous for changing out coils often lol so maybe the coils I bought from that random website ended up being crappy. Dcfluegel also brought up that the juice I was using could have been causing the chemically taste. So both the coils and the juice combined could have been causing the issues I suppose
If you are positive that your battery is producing enough power, then you need to turn your attention to the tank system -- before you do that though make sure that the contacts between your tank and your mod are completely clean.... Make sure there is no e juice, dirt, oil, or any other substance on the contacts. I regularly clean my contacts off with qtips and rubbing alcohol.
If your connections are fine, then remove the coil from your tank. Get yourself a new coil somewhere and prime it with e juice first, then install it. Make sure the new coil is the correct one for the Nautilus tank. Put your mod setting on the lowest voltage/wattage it will go and take a few tokes off the thing. Slowly turn the voltage up by a couple of tenths of a volt at a time. Each time take several more puffs before increasing the voltage again. You will eventually reach a voltage where the the flavor starts to taste a bit funny or burnt. You then know you have reached the max voltage for that coil/wick.. Then back off the voltage a bit and the funny taste should no longer be there.
If this method doesn't work and it starts acting the same way, then the only other alternative is to turn your attention to the e juice itself. Higher VG juices are thicker and as a consequence do not flow very well into the wick (on the Nautilus tank). Other larger tank systems can handle thicker juices much better and never have this problem. When that happens you will get burnt taste and low vapor production......... Once you burn a coil like then they are no longer fit for use and need to be replaced because you will never get the burnt flavor out of them.
So to solve this problem it would be a good idea if you use a thinner e juice with a lower amount of VG in it and also replace the burnt coils at the same time. This should solve the problem.