Fist off working with:

1996 S10 Blazer Vin W 4.3

Parts replaced:
CPI (OEM)
Timing (full set gears and chain)
Dizzy (OEM)
Cap (OEM)
Rotor (OEM)
Wires (OEM Equal)
Plugs (OEM)
Vac lines
Remote Oil lines (OEM)
Fuel filter (OEM)
EGR cleaned
Intake gasket (new)
Cleaned intake when did gasket
Cleaned TB and MAP
TPS (OEM new)
IAC (OEM new)
Exhaust (new from headers to cat to tail pipe)

Checked all grounds and they are all good, tight, and clean

Timing set per DYI section (everything lined up to a T)
Fuel Pressure 62 psi on key on 60 at idel

Issue:

P0304 no cell light (swaped wires and Popit no change, even did new plug no change)

Compression test:

2 120
4 95
6 120

Wet test on all 3 showed close to no change

But cannot get rid of the P0304 code with scan tool connected either at idel or drive test

 

#4 is showing low compression as compared with the other cylinders. If putting oil into the cylinder did not have any appreciable difference in compression reading, then the valves are likely at fault.

 

UPDATE

Took it for a nice long drive, code or SES didn't show.
highway MPH 50 nothing, 55 nothing, 60 nothing, 65 nothing
Town MPH 5 nothing, 10 nothing, 15 nothing, 20 nothing, 25 nothing, 30 nothing, 35 nothing, 40 nothing

Now sitting at idel when I went to park it, BANG there is the code again
Cleared and restarted just sitting at idel and again shows itself P0304

NO SES light

Just shows on the code scanner

History shows P0300
Current shows P0300
Sense clear P0300
live data shows P0304