I have a Revo STX filled with 14# berkley pro grade 100% florocarbon mouted on a 6'9" MH LTX Carrot Stick.  This combo feels great but backlashes severely.  It seems that every third cast is a birds nest and does not matter what weight, size, or type of lure that is used, especially if I try to get some distance on a cast. This problem is only evident on this combo because I have no problems casting braid, floro or any type of line with all my other rods and reels. It even backlashes with fairly heavy thumb pressure.

Has anyone else had the same difficulty controlling these reels or does it sound like a faulty reels.

I was going to say it's that dang floro until i read a little further. And since you have experience on other bc's, can't use that excuse either. And i don't even own a revo. Why am i even ....

Well, the Revo may be partly to blame.  The Revo has the least amount of backlash control of any reel I have thrown.  

I had a Premier that had that problem, among others.  On mine it did not matter where you set the brakes, it applied the same amount of stopping power.  After talking to a few people, this seems to be a recuring problem with the Revos but an isolated one.  If you can, I would exchange it for another one.  Several members here have them and have reported no issues what so ever.

It's not a faulty reel, it's faulty set-up. Set up properly, the STX will cast with no thumb control at all (except at the begining of the cast).

Set your reel's cast control knob so that you lure barely falls when you jiggle the tip of the rod, and stops when you stop jiggling. If it falls when you don't jiggle it, it's set too loose. Even a little tighter may be necessary.

Set your brake to about the 1/4 position for lure 1/4 oz to 3/8 oz. A little more as lure weight goes up.

Next, practice. It is an unrealistic expectation that the STX must cast like every other reel you may be used to. Once I got used to mine, it outcast every other baitcaster I ever used.

Backlashes are 99.9% user error.

Backlashes are 99.9% user error.

That's heresy!