What cossie is it? what ecu and TPS?

The plug fix simply proves teh ECU is sending voltage to teh valve, so it is being told either:

1) The engines cold.
2) The throttles open.
3) The engine speed is high.

The above scenarios all send a drive signal to the valve. All i can think of top of my head pal. If its 2wd, you can unplug the TPS and see if it helps, if it does, the signal error is there...

Just off out to eat so will be a while before i reply....