TVR S1 Revs dropping when cold

[aruck]

Hi all,
Looking for some inspiration...
When the S1 has been driving for a while everytime I slow down for a junction, etc the revs drop off completely to the point where the car stalls.
When cold the revs are idling happily at about 1k revs.
Its been at the garage and they can't find the problem. It needs to be driven for at least 10 miles before the problem starts.
Anyone experienced this or got any ideas?
Thanks,
Adrian

[MJG280]

Assuming it's still a 2.8 if it’s running ok during normal driving then it may be the Auxiliary Air Valve as it provides the fast idle during the warm up phase and is bolted to the front of the ribbed air chamber with 2 black pipes going to it, one from each side and a black electrical plug. When the engine is cold, the valve is open.

If the throttle is incorrectly adjusted and closed up on tickover the Air Valve is providing enough air but when it closes on warm up there is not enough air getting through the throttle. Try adjusting the throttle by screwing the adjuster anticlockwise.

or it could be leakage in any of the air pipes weakening the mixture.

[aruck]

I have adjusted the throttle previously but this means the idle is too high.