Your talking about the banjo fittings right
They are a bitch to get off but be persistent you will be able to crack them
I changed mine even tho it had just had a major service 15 xxx kms before hand I did it for peace of mind also dosnt hurt either. :p
Use a socket with a hollow bar on the end to get more leverage and it will be easy as. And for te top one go from the top either get someone below and above to help or use heaps of extensions and a bar to get leverage or take it to a mechanic even it's a 20 minute job if he knows what he's doing.
It's only hard the first time ahah
That's probably a major part your issue
Clogged fuel filter replace it I would suggest I just used a ryco one aswell they need to be changed probs every 20xxx kms, so once a year maybe earlier if you give it a hard time better to be safe then sorry and there only 20$
But when you do get it off clean the fuel off the outside and try and blow through it if you can't then it was badly clogged or if its easy too then it may have been fine
Compare how easy it is to blow through to the brand new one. Also when I pulled mine off wasn't extremely hard to blow through but defo required force and the amount of dirty fuel that came out was a little disturbing.
Seemed to help the car run smoother and fuel consumption went down, performance and fuel pressure went up :)
So give that ago asap