I bought a 1997 'R' plate BMW 520i yesterday, 90,000 miles, full service history, but the car has only done 4000 miles since June 07 when it was last serviced. The car feels massively underpowered almost to the point I think it's going to stop going up a hill. I have a Diagnostic man coming out on Friday and he also can retune, do you think a quick retune with his computer should do it??