scoobzie

hi guys i ve got a my00 2000 turbo it has started to hesitate between 2/3 grand when you slowly build up speed but when boost comes on its fine when you floor it in every gear its fine it all started after i serviced the car
parts replaced
1.maf sensor
2.lambda sensor
3.plugs twice
4.oil filter
5.airfilter
6.cleaned boost solenoid
7.checked coil pack and leads all look fine
8.drained some oil incase to much put in
there is no cel light coming on it happens now and again worse when cold resset ecu twice anyhelp will be greatly appreciated cheers scoobzie