aj26 is easy

look at your heated o2 sensor voltage (upstream) on wide open throttle. if they peg 0 volts you have fuel starvation

https://cimg5.ibsrv.net/gimg/www.jag...7024b03e9e.jpg
one filter was completely covered in sludge. One partially. No wonder fuel pressure was down!!

RESOLVED.
Took the car for a test drive this morning on the new pumps. Had a few warnings showing as I had dropped the rear subframe aswell as pulling the tank.
Took the opportunity to change the diff oil.
Anyway, initial driving was ok until I hit 3000rpm. Car started kangarooing. I pulled over and cleared the codes with my cheap reader. After that drove perfect. Like new. Safe to say i was over the moon with it and took it for a good drive including motorway. Only issues i have now are a crackly radio and an indicator direction bulb not working in the speedo. I will get to them!
many thanks to all who offered assistance and to those who suggested fuel pressure you were perfectly correct.