Sorry guys, I've missed out some key information here. Before I took the car for mot I had been getting fluctuating revs at idle, jumping between 1 and 2k and sometimes steadily increasing until I found a gear/cut the ignition. It was intermittent but seemed to have ironed itself out, it wasn't until the emissions tested badly I thought it might have had something to do with it. At the time I thought it might have been the throttle body or a vacuum leak, but I didn't investigate any further and as I say, they're having trouble programming the throttle now. Don't know if that clears anything up