more idler arm problems...

Probably you are missing the center steel tube that goes inside the idler arm.
Use Google "Images" to see all the parts like this [ame="http://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1016&bih=628&q=dodge+dart+idler+arm&oq=dodge+dart+idler+arm&gs_l=img.12...3188.9735.0.11625.20.11.0.9.2.0.156.1327.3j8.11.0...0.0...1ac.1.11.img.sNXmDh2CpVE"]dodge dart idler arm - Google Search[/ame]

On the rotors you have the bearing the washer the nut and then the lock cap for the cotter pin.
I spin the rotor while tightening the nut with a pair of pliers till I can't get it any tighter and then back it off to the first cotter pin hole that lines up.
There's NO WAY it should be tighter than this.
I'm talking tightening it with the pliers sticking straight out from the hub.