Hi all, newbie here, I have not long got my first volvo, 850 t5, with a 300 bhp remapped ecu, turbo back free flow exhaust, after market air filter, mbc, and uprated competition coil leads. my first question is, why is my trip computer, constantly showing 5.5 mpg, I've tried to reset it, and disconnect battery by nothing works. my second question is, i seem to be getting fuel cut anywhere from 12 psi, from what i have read, this shouldnt kick in until about 15 psi, could spark plugs cause this, or am i looking at something possibly expsensive to fix? i have checked all vacuum and air lines, and all seem well and seem to be holding close to 30 in/wg on idle, and boost holds until the cut kicks in.

I'm a bit worried with both problems, I cant afford to be running a car that only gives 5.5 mpg(or is this just the computer be dodgey, and can it be fixed), and the fuel cut is god damn scary, and can make you look a bit like an idiot. thanks everyone.