I'd put a fiver on it not being the MAF sensor. It sounds like you could have air in the fuel system, or a blockage in it. Air leaks can be caused by the priming bulb leaking, one member (ETV) suggests wrapping it tightly in cling film to see if the problem gets better.
Also, there are leak off pipes connecting each injector to the one next to it, and these can perish over time and let air in. Other culprits are the fuel filter bleed screw being loose, fuel filter drain widget (plastic thing underneath) being loose, fuel filter pipe connections not secure, or fuel connections to the fuel pump not being secure.
The priming bulb goes soft normally, but a few pumps make it go hard, this is how the three L series Diesel cars I have owned have been.
My experience with the fuel pump timing being out is that the car is a pig to start, but as soon as it fires up, it drives perfectly, so I don't think it's due to that.