I have a bone stock 305, 283 heads edelbrock performer intake, edelbrock carb, two rocker arms came loose and Ive tried every way there is to adjust them but my car still acts like it's kind of missing mid range yet idles well and runs well at high rpms. Timing couldn't have moved?? Help I'm at a dead end...

 

The rocker studs could be pulled out. Stock they are just pressed in. You could have something else going on but I would check this. No unless the chain stretchered or something the cam timing would not have changed.

Check all your spark plug wires.