Rough idle, p0300 code

[ewx088]

Hi guys, this is my first time to post, ive been reading a lot of threads but cant seem to find the exact answer im looking for.

07 tahoe Lt with 168000 kms in it. Car runs fine since then and made a tune up just last month. Changed the spark plugs(ngk), plug wires(acdelco) and an oil change.

Today i was driving then suddenly the car was vibrating hard from the engine,the car didnt die but very rough in idle. Plugged in a scanner and threw a p0300 code. Made some tests and cylinders 1,2,4 are misfiring hard and cylinder 6,8 a little bit.checked my wires and they are all intact.

Where do i start looking? Is fuel a possible cause? Because the car was near empty yesterday so i gased up just near my houset then parked it already, today i went to places but not too far then suddenly the shaking began.and is it safe to drive the car because im out of town and i need to drive around 150kms to get back to town and to a dealer if ever.

Need help pls.....

 

[ewx088]

Just an update, problem still exists. Drop the gas tank and drained it and filled it with new gas to eliminate the possibility of bad gas. Also cleaned the throttle body. I also disconnected the maf sensor plug but nothing happend, still misfiring hard.

Is it possible that the new plugs after a month of installation are now gone and causing the misfiring? Havent tried swaping wires and plugs yet with cylinders that dont misfire.later will do that.

One more thing, when the shaking/misfiring started with blinking CEL, it was simultaneous with the traction control light and warning for service of stabilitrack and traction and is hard shifting. Is the 2 related? Maybe a computer issue?

Another thing is that i didnt lose power, acceleration up to around 60kph is a little shakey and rough but 60kph up it runs smoother and still fast.

Any other suggestions is greatly appreciated!

 

[samotahoe]

could be bad plugs that were dropped in handling?

your wires, try to double check firing order, maybe a couple wires were crossed in the process

pull those plugs and see if anything is out of spec