If you have the cash then I would recommend going for the newer version the HR.
Don't be fooled by the bulge on the bonnet as that was a very popular upgrade on the older/earlier DE cars.
To be sure, just lift the bonnet and check that it has two air intake boxes.
The early DE version and Revup only have the one.
Very easy to replace, just remove cam covers, fit new gaskets (supplied) and refit with new cover.
Drilling and cutting are only required if you are replacing the 6 x oil seals.
These cam covers come with the 6 new oil seals already fitted.
For sale, 1 pair of new VQ35DE Rocker/Cam Cover assemblies complete with gaskets and fixing bolts.
Cure your oil leak from inside the cam cover to the spark plug aperture at a fraction of Nissan dealer prices.
Nissan will charge you the following:
1 x Pair of Cam Covers: £602.80:
2 x cam Cover gaskets: £38.92
20 x cam cover fixing bolts: £183.12
Nissan Price Total of £824.84:
My price: £250.00.00 shipped to your door: (Mainland UK)
I only have 5 sets in stock at the minute.
Drop me a PM or post your inquiry up here on the open forum.
Without a code you are guessing I am afraid.
Plugs, coils, cam position sensor, injector, etc etc. are stuff that I would be looking at.
Perhaps might be a plan to let it develop until it stores a code.