940SE 16V Auto Engine cutting out/not re-starting

I have had an ong-oing problem whereby the engine randomly cuts out and will not restart immediately. I took advice from a fellow member (Ian Fewtrell) to clean the throttle housing. This was indeeed dirty so I cleaned it as advised. However, the problem is still occuring.

The problem presents itself either as an engine stall at low speeds (often while idling) or at higher speeds while the engine is on load. In both cases, the car will not re-start unless I wait for at least 2 or 3 minutes. It turns over OK and sometimes it splutters but dies. As a basic mechanic, it seems like either fuel starvation or too much fuel preventing ignition. I'm at a loss at what to do next other than replace the fuel pump relay. I've already replaced spark plugs and ignition leads. I've a feeling it's been getting worse since I've been using the air-conditioning more frequently in the hot weather. I'm hopeful that someone can pin down the problem.

Many Thanks - Dave Harper, London