Poor Running. Engine Stalling

Hi guys. This problem has got me stumped, really strange. (1999 Rover

Today, my car broke down. Basically what happed was initially, it lost power and nearly stalled until I dipped the clutch and kept the revs up (spluttered a bit), then about 1 mile later it done the same, but actually stalled and wouldn't restart. It would crank, but not fire.

I got recovered and took a look around the engine, all seemed OK. My instinct said it felt like a fuel problem, and I had just refilled with fuel before the problem started, which made me wonder a bit.

I took the fuel return pipe off the rail and I had plenty of fuel pressure. After doing this, the car started, and when revved gently seemed OK, but when put under load it would try to die, or would die. It would restart after cranking a bit though.

I took a sample of the fuel, and looked a nice pissy yellow, smelt OK and didn't appear to be contaminated.

There was plenty of vacuum to the Fuel Pressure Regulator.

I visually checked throttle position sensor, coolant temp sensor, engine management connectors, which all looked OK.

Then after the car was let to stand for about an hour, the problem cured itself! I have done 8 miles since and everything seems fine. Strange!

Any ideas? I have the feeling I will break down again as I haven't done anything to cure it.