There's a "Sweet Spot" with the Ithakas when it comes to juice control - if you over-juice them, you will loose vapor & flavor - you are flooding the coil & cuts its efficiency and ability to produce vapor (flavor). If you under-juice them, you will get a slightly burnt or slight metallic flavor.
One trick I've found is that if you are loosing flavor, but not getting the burnt/metallic taste; shut down the juice control completely, and vape it horizontally for a little while until it starts coming back to normal (you will be using up the excess juice in the wick & won't be getting as much juice into the "automatic" juice pick-up), then open up the juice control again about halfway to where you were before and fine-tune it from there. It sounds complicated, but its really not.....you will develop a feel for it as you get more used to the device.
When you rebuild a coil/wick, you usually need to "tune" it again a bit since no two re-wick/coil jobs will be exactly the same. I had the same issues when I started using Oddys a while back....now I can usually get them (and my Ithakas) dialed-in in a few minutes.
BTW... I also generally just dry-burn rather than re-build. The only time I rebuild one now is to try a new configuration, or if I'm using Silica (not Ekowool) wicks when they finally go south. In my experience, regular Silica wicks can only be dry-burned a limited number of times before they start giving off a burnt flavor, or disintegrate - the Ekowool wicks are just about indestructible.
Have fun....