hard start and hesitation acceleration

New to this but desperate for some answers. I have disco 2 03 auto, 175,000 miles.
6 month ago it developed a starting issue where" hot or cold" it would start for a second then cut out. After this I would have to turn it over for around 20 to 30 seconds before I could hear it trying to go. Once started it runs smooth as ever, although it has started recently produced an intermittent acceleration problem where it will have a temporary loss of boost for a few seconds then go as normal.
I've changed fuel pump and filter, bleed valve, cleaned maf, cleaned turbo, cleaned ecu plug and put a non return valve in fuel filter housing as mine was the one they stop putting them in. each of these things worked for a few days before problem returned. I know of a few other things I can try but fed up of wasting time and money and not getting anywhere. Can anyone shed any light of what it could be. thanks

I know nothing about discos but do they have and if so
leak off pipes that's if yours is diesel if so change em . if Im completely off track hope ya get it sorted

it is diesel but not sure about leak off pipes. I will have to look into this. Thanks

From what I can find out disco 2's don't have leak off pipes.

I'm assuming it's a TD5. This would have injectors that are actuated by the camshaft, and which are opened and closed electronically by the ecu. No leak off pipes as such, though there is a return pipe. I think it might be to do with the fuelling. Might be worth trying a new filter. Might also be worth running it through the purge cycle before trying to start it. If this improves matters is suggests air is getting int the fuel or that the fuel is draining back into the tank while the engine is not running.

My TD5 defender had a few similar problems - the starter would sometimes spin for a while and the engine wouldn't start, and there were occasional curious flat spots where you'd press the accelerator and nothing would happen - the engine speed wouldn't pick up at all. Annoying when trying to pull away from a junction or overtake something. This wasn't often, just once every month or two. Then the ECU failed completely. With the new ECU this doesn't happen at all. I'm not sure how the ECU creates these symptoms but I can't help feeling that this was some sort of fault in the old one.

Tried new air bleed valve, non return valve, filter the lot. I know oil runs through injector loom and gets in the ecu but I've checked mine and cleaned connector and also let a few drops of oil out of ecu by leaving stood up rite to drain out. Nothing major and didn't change a thing. I agree it is sum kind of fuel problem or air leak tho. Thanks for your reply

Don't rule out the loom, I think any oil in there isn't good. You need to think of it as a service item really

My next job was to change the loom, open up ecu and blast it with contact cleaner then seal it back up again.