injector 3????

[S13 240SX]

my injetor 3 acts funny when I push on it.. i was checking for leaks and no leaks but injector 3 doesn't seem to be in all the way so when i push on it just a little bit it makes the motor act all funny, rock and forth and stuff. So I've done the same thing with all the other injectors to see if other injectors would make the motor do the same thing and it doesn't.. so is there something wrong with injector 3?