car won't rev smoothly

[catch]

All the pipes are connected up to the valve and seem to be in good condition.
Would the ECU have anything to do with this?

[catch]

Tried disconnecting the overrun -cut-off valve - no difference.
If i rev the car and then press the throttle valve switch by hand the revs drop then climb back up a bit. Is the normal? Or should it stay idling when this is pressed?

really starting to run out of ideas now.....please help! 

[catch]

Now i've cleaned out and tested the overrun cut-off valve according to the Haynes manual. The meter readings are all fine and i can't hear the valve working when i press the throttle switch.

So....what's left to test?

All I can think is the control unit behind the centre console is knackered. Anybody got a test for this?

[Mr Blue]

Try the air flow meter.

Mine is not idling smoothly and have narrowed it down to this

[catch]

I've cleaned the airflow meter now, a little bit of old oil in there but not much.
I've done all the checks on the airflow meter according to the Haynes manual and it seems to work perfectly.
The plate is set up correctly and it moves freely in all directions.

So what's next. The Haynes manual says to change the controle unit behind the centre console. I thought all this did was regulate the ISV though?

Any ideas would be very much appreciated! 

[catch]

anyone that can help?

[markmarky0]

i have this exact same problem , its really anoying me and sounds like im a noob racer trying the rev around at every stop !
I tried cleaning the ISV still no worko,have a feeling it might be the gaskets somewhere leeking air :s , throttle body maybe i dunno.  let me know how it goes,
Mark

[monzablue16v]

Mine does it intermittently as well. I thought I'd cured it when I rebuilt it but I've had it doing the rev to 3000rpm when I stop again recently not amused. going to have a fiddle again tomorrow.

[DarnPB]

Check the throttle body for wear. Where the throttle spindle goes through the body of the throttle, get hold of it and see how much play you have. If excessive, then you will be letting air in and thus running lean, affecting the smoothness. These symptoms will usually be intermittent. I have rebuilt an engine from a Morgan because of a burned out piston caused by this.

[clipperjay]

I tried cleaning the ISV still no workoMark

You need to swap out a ISV that you know that works, cleaning it will not work if the things is jamed full of sh!t.
The symptoms are rought idle and high reving around 2k-3K RPM.
MarkIII's have a ISV you can use in scrappie, but this is the most likely common fault with idle hunting.
Unless an idle mixture screw has fallen out from the throttle body which always catches people out.
Other possiblilites least metering head is starving the fuel regulator and injectors of fuel.( a pressure test will tell if this the problem)

Jay