How to test injectors

[2000LSMichael]

I am still having starting issues with my 2000 V-8 LS. After it runs, and I let it sit for 10 minutes, the car starts hard (like the 20+ posts that I went back and read).

I already changed the MAF, all 4 oxygen sensors, the idle control valve, coils, and spark plugs.

I have read pros and cons to experiences at the dealership in find which injector is leaking. Can the dealership tell me which one in particular is leaking?

Thanks,
Michael