Peugeot 307 hdi turbo diesel 2.0 110 bhp LIMP MODE?

I have a Peugeot 307 hdi turbo diesel 2.0 110 bhp I have recently had a new engine and all new filters, cambelt ect and my car has gone in limp mode and won't let me past 3000 revs engine management light came on and unblocked diesel filter,antipollution fault light has gone off now and still in limp mode don't understand it can anyone help please