misfire on cylinder 4,new fuel injector not working.what do I do?

Are you still under warranty? Lemon laws are different in each state but pretty much say if they try to fix the issue 3 times and it still bad then lemon law kicks in, again each state has its difference. If you are still in warranty they should fix it at try another dealer.

Don't refer to anyone who can't fix or at least test this problem as a 'tech'.!! Take it to another shop/mechainc! Possible or most likely faultly injector driver/circuit. Was this at a dealer for the repair?