Having trouble engine. Will start ok and if you take it steady will rev up and down as it should. However, when you quickly rev it at any revs it just dies. Have tried different parts such as the distributor, mas, ecu. Fuel is not the problem as mechanic hooked up a fuel system to injectors at 70psi and routed cars fuel back to return line. Revved engine up and disconnected tsp and engine acted as it should. The engine acted the same for all the above. Any ideas would be helpful. Thanks.