The power drain of cloaking is already covered: "Due to the enormous amount of power required to generate a cloaking field, there is by and large not enough power available to also power the weapons and shields."
You want to fix claok and deal with griefing?
Don't nerf what cloak does. Improve the granularity of stealth dection.
There should be a state where you know the direction to cloaked ships (e.g., the map marks a spot where a cloaked vessel should be) and a state where you just see the cloaked ship. if the first was achievable in some relatively "simple" manner - like running your Aux higher then that of the cloaking ship, and being equally skilled in Sensors/Sensor Array, you would negate the possibility of cloak-griefers that hide and never come back.
For example, a simple model could be this:
We have two "cloak detectin rates".
The primary detection rate is where you actually can see and target a cloaked ship.
The secondary detection rate is where you know its actual position.
Primary Detection Range is 1 km. Secondary Detection Rate is 5 km.
You mutliply this value by 1 + (Starship Sensors + Starship Operations + Starship Sensor Array Skill / 100) + (Aux / 100) on your side and the enemy substract his own values for that.
So if you run 50 Aux and have a +50 total skill modifier, you would have a primary detetion range of 2 km and a secondary detection rate of 5 km. Of course, if the enemy BoP has the same stats, you're back to 2 km and 5 km.
If you are fairly maxed for scanning, you might run at 125 Aux and have a total skill modifier of +100 (you could get more). This gives you a multiplier of 3.25, so you could "see" the presence of cloaked vessels. Assuming the "average" cloaked vessel gets a -0.5 to that, still a 2.75. So you can detect its presence from 13.75 km. Without needing any power so far.
Now we add powers. One of the latest updates added a bonus to Stealth Detection and Stealth Rating from Emergency Power to Auxillary.
Emergency Power to Aux might add 0.1 * Rank + (Starship Engineering + Auxillary Maintanence + Auxillary Efficiency / 100) to this equation.
Now let's add Sensor Scan. It is currently very strong for detection, so let's keep it that way.
Sensor Scan might add another 0.2 * Rank * (Starship Sensors + Starship Operations + Starship Sensor Array Skill / 100) + (Aux / 100).
Now let's give Science Ships another 0.5 to the multiplier.
So a Cruiser or Science Vessel with Emergency Power to Aux II and having a skill total for the above of +50 would get another 0.7 to the modifier for a 3.45 for a range of 17.25 km.
Using Sensor Scan II for example, a Science Captain with the above stats would get another +0.9 for a total of 3.65 for a range of 18.25 as secondary detection rate and 3.65 km as primary range.
Usuing both together, he'd get a 4.35 multiplier and a primary detection range of 4.35 km and a secondary of 21,75 km. I think you don't really get much sensor information beyond 20 km anyway, so this should be entirely sufficient. Any "cloak griefing" beyond that range would also work without cloak.