vz sv8 running in a shocking manner

[perthvzsv8]

hi guys'
a while ago my vz started running so bad its off the road, for now.
car is at 73,000kms, so i thought what the heck i will change some items
items changed: plugs
leads
coils
injectors
result is the car still runs like rubbish
when i took the old plugs out one side of engine they were perfect looking, but the other side were black as, like real bad.
i had headers fitted a 1000km ago so.....i was thinking that my oxy sensors have gone bad on one side of the exhaust system, at least.
what do you guys think of that diagnosis, for what it is worth nothing came up on the dash as to any potential errors, which i found odd.
i didnt mind replacing the other stuff as figured it would not hurt to replace the leads, plugs, injectors and coils.
the coils i got are original gm ones, the leads are thicker aftermarket ones, the plugs are the platinum ones and the injectors are bosch with the correct numbers on them, so what next? oxy sensors?y appreciated
oh yeah the car smells of unburnt fuel and that its dropped cylinders (maybe the 4 on one side ?)
also why did no limp home mode come up on the dash, would it help if i bought another ( long story) envyous customs fault reader, just in case.
any help really appreciated, as im running out of ideas
thanks guys, Dave Baldivis WA

 

[Fu Manchu]

Did you buy the spark plugs from a retailer or online? There are shinto loads of very good counterfeit plugs on the market. They will have your car running like crap.

Have you got a vacuum leak?
Are all the injector plugs connected up properly?
Compression test?

What are the O2 readings like?

Air filter ok?
Throttle body ok? Need a clean?
PCV system clean?

 

[EYY]

Check your crank angle sensor and wiring…

Standard issue after fitting headers.

 

[perthvzsv8]

Hey guys thanks for prompt replies.
Compression good, have not checked crank angle sensor wires will do!
Checked for leaks all good
Throttle body is new about 1000 kms of use
I bought plugs from a retailer