I was wondering if somebody could offer advice as my 2007 ST is starting to run a bit rough. It revs smoothly through the range but above 3,000 rpm there is a fast metallic knock, also the car's revs have started to race occasionally then idle very low.

It is under warranty until august as has been in over a week ago and they found nothing wrong with it and no fault codes. I'm booking it in again tomorrow as it's just not right. A few of my family have driven it also and said it doesn't feel right so I don't think I'm going mad. When it goes in i'll insist on taking them for a test drive. I just thought somebody might be able to give me a clue about what it could be?

Thanks, Richard.

Its hard to diagnose things without hearing them for yourself, especially tapping noises and knocking noises, and without a fault code present it will be hard to find out why the car is not running right.

It's annoying to say the least, one thing that springs to mind is I cleaned the throttle body a short while back and I was a bit rough with the butterfly valve. Could this have an effect on the running?

Was the car running ok before you cleaned the throttle housing.

I'm pretty sure it was and it wasn't immediately after I cleaned it that I noticed the problem but it wasn't long after either. Could just be coincidence.

HOw many miles have you done since cleaning the TB. It will behave odd for around 150km's (100 miles) or so, while the ECU readapts.

Are you using crappy fuel?

It was about 500 miles at least since I did it. Use shell regular octane all the time and always have so doubt it's the fuel.

could be spark plugs on the coil pack mate as a thought. Sounds weird about the noise thou but if a car is running rough, this is first thing i would think of

Might have an air leak in the inlet system.
Might have a blocked/wet air filter.
Might have a HEGO going down.

Might have a leprechaun hiding under the bonnet

or a sausage blocking the fuel line. i love the word sausage. sounds ace