2008 CLK 320CDI Won't go past 3000rpm

Hi guys,
I've owned my CLK now for about 2 months and the past 2-3 days it's been playing up unfortunately. It's really slow and won't go past 2500rpm-3000rpm, I can't figure out why exactly. Most of the time it's fine and you can go as fast as you like and be in high revs, but about 30% - 40% of the time it will be 'limping'
It is due a service B in about 2 weeks time so maybe it's something to do with that, I don't know.
Any other ideas on why it's doing it?

 

Possibly the MAF sensor is faulty and the car is going into "limp mode"
The only way to be certain is to have the fault codes read and see what faults are current, and which are stored (and can be ignored)
The first thing is to find yourself a local MB independant tech (indy). He will have Mercedes Star diagnosis equipment which can pinpoint the fault live. An indy will save a fortune on labour costs and will use OEM parts and update your service records, just as main dealer but much cheaper.
Where are you located so maybe someone can recommend a good indy?

 

Exhaust back pressure sensor?

 

Hi Dean welcome to the forum. This can happen for a whole host of reasons without diagnostics equipment its pointless guessing I found this out the hard way. Even a cheap ebay reader can pinpoint you in the right direction sometimes it's saves me a fortune but these little OB2 readers don't show up everything. As above its best to get it checked with star which will show up the exact issues.