XJShane

I have a 99 cherokee sport and love it but i need to fix a few issues. My main problems right now are i have a CEL for the #2 shift solenoid i believe it was. I assume that this is the cause of my shifting problem and starting out in 3rd gear every once in a while. My question is- is there any place to get these things cheaper? and when i do replace it whats the best auto trans fluid to put back in? also my leaf springs are shot they're actually bending the opposite way now. what brand would you all recommend for replacement? should i do heavy duty for the slight lift and better ability to handle a heavy trailer?