Hi Guys I'm having a problem with my st180. I've had the car since July it's on 30k miles, clean history and 1 previous owner. 

I replaced the Maf sensor yesterday as it had about 80% power loss and had a "service engine now" message accompanied by the spanner light on the dash. It threw up a MAF sensor fault code, so I had it cleared and replaced the MAF with a new HAAS one. Drove it home after work and everything felt better than ever. 

On the drive home tonight I gave it a few pulls to make sure the car was still operating as it should and as it hit 4k rpm the car really struggled to get past that and started to violently stutter and kangaroo. I tried this a few times to make sure and it's a definate issue. Under 4k rpm it operates as it should and there is no warning light this time. The only modification to the engine is an ITG induction kit that I've had on since September with no issues. 

I haven't checked for boost leaks or anything of the sort yet as I finished late from work. I quickly checked the secret dash menu for fault codes and it said "none". 

Anyone have any suggestions or ideas for what this could be and how I should tackle this? 

Thank you. 

*Update*

Came out to the car this morning and the "service engine now" message has popped back up with the spanner light again 🙄 unlike before it has come on straight away rather than after 15 minutes of driving. Checked the secret dash menu and still no codes have come up. 

There will be a fault code logged, but you're probably going to need an OBD reader, or something more specific like forscan to pick it up.

I imagine so, it's in with my mechanic currently for something else unrelated so I'll see what he comes back with. Haven't heard anything yet. 

Turns out it has a new fault code which is P2279 (intake air system leak). It has been wiped for the meantime but still doesn't feel right, so I'll check for air leaks along my intake system. If I don't find anything then my new MAF sensor could have gone bang after the first day 🤔 if so I'll exchange the faulty sensor, get the code wiped again (if it comes up) and fit the new sensor. 

The only other thing I could check is the throttle body for leaks but not sure how to go about that? It could need cleaning? And then I would have to let the car relearn the throttle position. 

Anyone else have any other suggestions? 

Did you manage to fix this? I have the same issue. 

I have a similar problem as well. Did you manage to fix this issue?