im in the same boat as you m8, but mine wont go above 3000rpm, i have the AA coming tonight so if i have any info i will let you know
EDIT:
the AA suggested either fuel pump (which he pointed to the carbon canister in the engine bay :/ or the MAF and suggested getting diagnostic investigation carried out.
after ringing various Nissan dealers to book my car in for diagnostic work, the earliest they could get me in was 10 days, so took it to my local garage to gauge some advice, they did a simple test and unplugged the lambda sensor (this allowed the gases to bypass the cat and exit the out the hole) and therefore allowed the car to accelerate, they pin pointed the cause to my cat which had collapsed.
as i write this its currently having its cat replaced, they suspect that the blockage in the cat caused the back pressure in the exhaust causing the engine to restrict the power so the gases in the blocked exhaust didn't build up.
hope this is of some help to you, i would suggest that simple check of removing the lambda sensor.
