hey people i think i may have a bit of a problem with my f reg xr3i mfi.....

im only getting 30 mpg but this may be bcoz of the really cold weather and my metering valve been open more but also is this affecting the fact that the car really struggles to get past the 100 mph mark not that i need to do that speed which is awhile since i did those kind of speeds so this is a new problem discovered yesterday so i will check all the usual plugs and leads etc etc just wondering could it be a worse problem than this????

cheers steve