wondered if any could help me out. recently started having problems with my99 sub. at idle speed its bouncing above and below revs and is occasionally stalling when coming to a halt. local garage replaced the ecu temp switch assuring me that would sort the problem but then they only just scraped it through the m.o.t because the revs were still mad and the emmisions were too high. any clues?

Do you have the MOT emissions data? It may help.

On a MY99 car, I'd suspect the MAF sensor - they are quite fragile.
Do you have one you can borrow from a friend to test?
You can buy a new sensor for around £70. Don't pay for a whole new airbox.

dont have a fellow scooby driver near by so cant test it. i`ve been looking through the other forums and someone else mentioned the maf sensor for a similiar problem.without sounding daft what is the maf sensor? my local garage suggested changing the lamba sensor.

you can run with the lambda disconnect for a while before the ECU realises.

It will probably run even smoother then normal with it disconnected, as it will not be using the Lamdda pulse to set the CO.
this will be very noticable when cold as the Lamda will always take longer to warm up. This is why you may feel slight surging when first driven of a morning with the sensor connected.

As mentioned hunting or stalling are usually MAF or Idle speed control valves.

i`ll probably go with changing the maf sensor as this problem continues when the car is warmed up. i`ll try it with the lambda sensor disconnected first. i hear that running the car with a faulty maf can blow the engine so i`m keen to change that just in case. cheers