I have engine light with P0300 code - Random.

I have engine light with P0300 code - Random misfire.
I'm experiencing rough idle, hesitates as I accelerate but then runs good at higher speeds.
On cold starts, I have to prime fuel by turning key on 2-3 times but then starts fine but again rough idle.
I performed fuel pressure test per your instructions.
Results were 60 psig with key "on", 50 psig when running, 57 psig with vacuum line to regulator removed.
When I turn key "on" and then "off", the pressure will quickly drop to 6 psig.
May be coincidence, but engine light showed up after replacing plugs and wires. Initially I had replaced with Bosch but returned plugs and wires to install AC Delco.
Checked each coil/wire with HEI spart tester and all had spark.
The vacuum line on the regulator is not leaking fuel.
After all of this, I'm thinking I may have
- leaking injector(s)
- bad fuel regulator since I leak pressure so quickly.
- I'm also suspect of the fuel pump although I performed the test. I find it a little louder than I think it should be and I'm not confident that 50 psig running is the OEM spec.(Please confirm)
Oh, engine vacuum runs about 16 in Hg at idle.
Also, I have a strong smell of raw fuel when idling for a while.
How to test injectors?
Additional regulator test?
Thanks,
Danny