air leek help!

Hey guys am having real trouble with my sportline and need some expert help. Basically a couple of months ago it started to run extreamly rough, especially from cold, i would have to leave it to warm up before i could put my foot on the accelerator, the car wouldnt cut out compleatly would just flood instantly, when it did get going i would get the odd back fire and performance was terrible and fuel consumption very high. Not being mechanically minded i put it in my local garage, and after much head scratching they couldnt find the problem. They changed the plugs, leads, coil, amplifier and still nothing got better. My next step was to take it to my local bosch servive center to run a diognistics check on it. After the check the guy came back to me and said that my warm up regulator was broke so i needed a new one, which i have purchased. The big mystery is they also said that sumwhere their is a massive air leak, but after searching for two days! They could find nothing. Does anybody have any ideas where this leak may be coming from? I have heard rumours on the net that their may be sumkind of air inlet valve that is exculsive to mk1s that the garage does no about, if this is true i would love sumbody to help me as i just want my baby back! Regards with any help  Sallly.

Get them to do a smoke test on the induction system, that will reveal the air leak.

Thanks paul will pass on all tips i recive. Just lookin at a post further down and sombody has mentioned an aux air valve, was wondering if this could also be my problem?

Is it definitely an air leak into the induction system? If the aux air valve stuck open, it would make the car idle high but the valve it not open to the atmosphere, flows filtered/metered air bypassing the throttle. Its possible that the pipework at the rear of the inlet manifold is leaking, or a clip missing, and has been overlooked by the garage.

I am surprised (maybe I should be used to it by now!) that 2 garages have looked at your car and not gotten it running right. It doesn't inspire confidence in the garage trade!