2003 Renault Laguna EGR Valve?

Engine Performance problem
2003 Renault Laguna Front Wheel Drive Manual 96000 miles

Hi, about a month ago the turbo went on our laguna. We had the turbo reconditioned and re-fitted, however there seems to be no power. The turbo is spinning but the rev counter will not go above 3000. We took it to the garage and they suggested that the egr valve could be the problem. And when we investigated into the engine, it seems like the guy who re-fitted the turbo had not flushed out the engine to get rid of the old oil so oil was everywhere, so someone also suggested that oil may be in the intercooler which could also be affecting the performance. Please could you come up with a suggestion?

Much appreciated