Hi all, I understand this is a VZ section, but was hoping someone may have a solution to my issue. My in laws car 08 Ve alloytec has came up with p0300 random misfire fault, also cylinders 1, 3, 5. RACV told them that two coils were gone and had to be replaced. So I got the job to replace them, only to find fault still comes up. I put 2 new coils into 1 & 2 fitted 2 into 3 and swapped 4 with 5, the fault still did not change. I also checked the spark plus and they all seem fine NGK platinums so I assume they have been changed. The car has 153000 on the clock. It has also had the right side cat changed for a previous fault, one O2 sensors also for another fault. I have tried searching posts on this but haven't been able to find a solution. The car starts fine every time but once revved over 2000 the miss comes back and the left bank is shut down. So after some more investigation tonight I found a vac leak coming from 90 degree fitting at the rear of the drivers side valve cover. The hose goes to a tee then one hose to each side of the plenum. I blocked these off but found no difference, I didn't expect to but worth a try. I then plugged in my code reader and reset the fault and noticed some variations between STFL B1 12.5% and STFL B2 6.25% average fluctuating but B1 always higher. I also noticed differences with the O2 readings, o2s 11 0.360v -14.85%, o2s 12 0.465v 99.21%, o2s 21 0.690v 11.71%, o2s 22 0.480v 99.21%. Not sure if this info is of any use but may mean something to someone clever on here. Any help appreciated, It is about to be sent to holden to see what they say. $$$$$ hopefully not.