sorry to hear that, just pm'd you

Most common reason for limp mode on the N54 engines are the vanos solenoids, but I replaced both a few months ago (check thread or service history for exact date), second most common (according to forums anyway) is the charge pipe, so hopefully it's that, would be a good opportunity to upgrade it if so get the codes read though anyway ofcourse to find out for sure, the N54 is incredibly popular in America and there's a wealth of information online, check out N54tech.com for some reading if you have some free time, everything from technical help to crazy 600bhp+ modified N54s