The AEV kit is suppose to come with brackets to adjust the castor. You should not have to buy new lower control arms just for that reason.... The jeep will feel flighty if castor is off pulling is not a symptom.
You can run a jeep without a SS. Take the one you have on off and see if it stops pulling it may not be installed in the correct location and adding a different one is just going to complicate your troubleshooting. If a SS is not installed properly you will feel a pull because it is trying to get itself back to where it thinks it is suppose to be.

 

Look at page 12 - 14 does your jeep have the brackets installed? http://www.aev-conversions.com/ishee...ensions%29.pdf

Also in general I would print this and look at your jeep does it have all the parts installed? I would do this in addition to just taking of the SS and driving the jeep to see if it stops pulling.

 

I don't see anything to out of balance with the caster. I would look at your left brake caliper and you said it was leaking fluid out of the left side? I would get that fixed and maybe something wore out and now is rubbing an causing drag on that side. Hard to say on a forum without seeing the jeep. Sounds kinda like your axles might be turned a little side ways.

 

 

Meant a pic of it head on so we can see how the tires look when it's "straightened" out...

 

 

Looks as if your left tire is pointing a bit to far left. Try the do it yourself alignment (tie rod) and pull it in...

 

Driver side tire....

 

How do I do the alignment ??

 

Is there a link I can use to do this? Or do I need special tools?