Abf running problems

Hi, sorry if this topic has been covered before but I'm struggling for an answer. I Bought the car a couple of  months ago and all seemed fine until fuel lift pump became extremely noisy, then car would cut out when driving or just parked ticking over, Having changed lift pump and putting correct fuse (it had a 25A for some reason!!) left it running on drive for an hour with no cutting out So I took it for a test run, was fine driving in 20/30 mph limits but when I went 3/4 throttle its started spluttering like mad, it didn't cut out though. Pulled over turned ignition off and on and was fine  until opening throttle up again, serious head scratching going on, if any one can help would be much appreciated.

the dead lift pump might have killed the main pump. but check the new lifter is actually able to supply enough fuel:


for the 'jumper' easiest way is fit a 17/18/100 relay into slot 2 and switch on the ignition for 30 seconds