I have a 2001 Vauxhall Vectra 1.6 (petrol). It's always having problems with the EGR valve - every six months or so we have to remove it and give it a clean out. We cleaned it out the other week and ever since then we've been having problems.

Not always, but quite often, when I'm going along at around 40-50mph I will put my clutch in to change down gears to slow down for a roundabout or turning and the revs just drop off and the car will stall. This happens even when the car is still going along at about 30mph, not just at low speeds. I can always tell when it's about to stall because the car will start to judder backwards and forwards a bit as I'm driving along. It sometimes also feels like it's pulling back a bit when I rev.

We've taken it to a couple of garages, but when they hook the car up to a computer, no problems are coming up. The mechanics can't get the car to replicate the fault when they take it out on the road.

We're reluctant to just start changing random components as the car is probably only worth about £1500 and we're thinking about swapping it soon anyway. Obviously we can't sell it if it's got a problem like this, but we can't drive it ourselves either!

Does anyone know what might be causing this? It would be great to have a jumping off point for fixing this!