Desperate, help rqd to solve engine problem.1998 2.0 norm asp V40 starts normally and engine accelerates normally when stationary, however runs very rough under any load when first started and for first 15 minutes, with no power until up to normal operating temp. When warmed up runs fine with no miss throughout speed range. Car has had multiple visits to workshop and has normal compression on all cylinders.No fault codes displayed. Has had new Volvo spk plugs, multiple new coil packs, new high tension leads. Any ideas please!!!