I own a '93 300zx convertible with 69k miles. I bought the ZX 3 years ago when it had 61k miles on it and was skipping at idle. The original owner said he had replaced all the injectors at 40k because of a skipping problem and that seemed to fix the issue. Unfortunately, the skip returned again right before he advertised it for sale. AFter buying it, I found the #1 injector was bad, so replaced it. One month later, the #6 injector went bad. Decided to do a switch over to a newer injector and changed all six with an adaptor kit so I could use the old fuel rails. Now the #1 injector has gone bad again. Is it unusual for the #1 injector to go bad so often?

 

Unfortunately it seems this is a very common problem on the Z32.

But... test the harness / connections first: http://z32.wikispaces.com/Injector+Testing