OK so I'm having a problem with power at the moment, I'll really put my foot down and it will shudder and sometimes slow down despite me having my foot down, at first I thought it was the leads because I had someone try to replace my cambelt last week (he could not get the locking pin to go in) and I he told me he had removed the HT leads, but the car had been doing it prior to last week just not as bad, if I put the car in third and put my foot down I'd occasionally feel a shudder but now it's all the time. Anyway yesterday I poured a load of Redex into the fuel tank and that seems to have improved things but not entirely and it still seems a little temperamental. I was thinking I'd replace the fuel filter as I think it's original and therefore 15 years old and 70k miles can someone tell me where it is as I can't find the info on Google, also should I be replacing my HT leads as well anyway?