my vn v6 motor is running rough through the rev range of about 2500 to 4000 then seems to run smoother. Sometimes when I start it it idles at around 1500 other times it idles normally at about 600-700. When driving it feels like it is starving for fuel at about 3000 but other times runs smooth but it is getting worse. Have replaced 02 sensor , has new crank sensor, tried putting second hand coil pack, map sensor, fuel regulator no change .The fuel pump is only about 3000k's old and brand new leads and plugs. Nothing seems to help .I cant get the faults out of it when I short the wires for the fault codes I hear a click but the engine light does not light up , maybe the ecu is stuffed, next move is to go to the wreckers and see if I can borrow one and try before I buy. How much is a second hand ecu worth at the wreckers ?

Thanks in advance for any replies

Ps the car starts first go every time and apart from sometimes idling fast it seems to idle ok and doesn,t have any miss when I free rev it up to about 4000 with no load , dont free rev it past that point. It doesn't matter if the car is hot or cold it still sometimes idles at 1500