I have a 2003 focus rs which today started with a running problem , but previous to today has struggled to start from cold and the fuel pump seems to buz a lot louder on prime up , problem started today after 2 mins of running it struggled to rev high , couldent climb smallest of hills , started to backfire but whould still idle. I was told whould be maf so bought a new one still no joy , car is throwing no fault codes up , I'm starting to think this is a fuel pump problem , any info or anyone who has had similar problem plz let me know , advice much appreciated