P0300 Misfire

[172Nathan]

Hi guys,
My 172 is running very lumpy and stuttery and has a flashing engine management light.
Plugged into an OBC reader it's firing up the code P0300 Random/Multiple Engine Misfire, with the following data freezeframe:
FUELSYS1: CL
FUELSYS2: N/A
LOAD_PCT(%): 0.0
ETC(°F): 100
SHRTFT1(%): 99.2
LONGFT1(%): 25.0
MAP(inHg): 14.2
RPM(/min): 1087
VSS(mph):0

I've replaced the coilpack and ignition leads for OEM as the coilpack had 2 bolt brackets snapped and was very loose, and the ignition leads were cheap 'double silicone race spec' ones.
The issue is still there, spark plugs were changed (NGK PFR6E-10) just 6 months ago.

I tried the unplugging injectors whilst the engine was running and the 2 on the left (drivers side) made the car go low RPM but the 2 on the right (passenger side) only changed the idle RPM ever so slightly.

Could they be the issue?
Any help is appreciated.

 

[bloke]

injector. cheap code readers seem to have problem identifying specific cylinder sometimes, especially if you have more than one dodgy injector.

 

[172Nathan]

What do you recommend I do? Just replace 3 & 4 and see what happens or the whole lot?
Cheers.

 

[bloke]

check resistance on them, looking for 14ohms ish. they are cheap enough new, euro do them for just over £30 each.