I had this sort of problem on my seat cordoba on a 2000 plate 1.9tdi. It actually turned out to be the ecu had got damp and it was shorting out where the big plug goes on. I had to open it up, clean some slight crud off the contacts and give it a good dry. I have since sealed it with silicone and wrapped it in a bag and am pleased to report I've never had the problem again. I don't know how relevent or helpful this would be to you but thought I would post it just in case. I'd bought a new throttle position sensor to.