1.4 MPI 2000 Sluggish + Crap MPG

Thought Id pull up this thread rather then make a new one....

Ive got a 1.4 MPi petrol and was mulling over whether to clear it out with some Redex as like Fabia1.4 it seems to struggle up hills and the MPG isnt so good. Just a few questions though:

1) Anyone ever done this and would recommend it?

2) If so, which one should I get...as a quick browse of Halfords showed 3 different types for petrol engines. Theres One Shot, Petrol Treatment, Injector Cleaner and Fuel System cleaner. Im confused as to which one I should get if I do try it :confused:

I bought the 1 shot fuel system cleaner for