Idle Problems
There are many reasons an engine will "rock." If you have a lot of mods, and from the photo it appears that you do, it may be the price for going fast. Some would even say it's a small price to pay for improved performance. If your cam is such that it has more lift and duration, and your injectors are larger, you MAF and TB are larger, you've moved into rumpty rumpty land. Great for midrange and top end, but a little hard on the lower RPM band. The only way to compensate for such mods is to bring engine idle slightly above the loping if possible. If you don't have any mods that would affect idle, then I would suggest the basics, a tune up, check and adjust all the intake components, and make sure the fuel system is working properly. If still a problem, check valve adjustments for equal settings on all lifters.