Clunk going into revers
 

I have an 2004 F150 5.4L. When I shift in reverse it clunks underneath my feet and won't shift in to gear for the first few moments that I push on the accelerator. Also the tachometer revs up and down from 1000rpms to about 1500. Wondering what's going on.

more than likely a broken rev band. Hardly any trans shop will replace a broken rev band because it is the next to last thing to pull out of the case. If you are that far in, do a complete rebuild.