P1233 Permanent Code

Optimiser

This morning while driving to work and stopped at the lights idling, the idle went up to about 1000rpm by itself, the engine light and the (2) VDC lights came on and the car would not go faster then walking speed with no throttle control. I turned the engine off and on again and the car drove normally (engine light still on) until I came to a stop again and the same thing happened as above.
My work around is when I'm stopped I use a bit of accelerator to keep the revs up around 1000rpm and when I get going again it drives normally. If however I let the engine drop back to its normal idle (about 650rpm) the whole issue starts again.
I can clear the codes using a scan tool and things again behave as they should, but after about a minute the problem starts again and "DashCommand" now tells me that the P1233 code is permanent.
Some research tells me that code is related to the Electric Throttle Control Performance-Bank 2. Apparently this can be related to the following:
1/. A faulty Electric Throttle Control actuator.
2/. ETC actuator harness open or shorted.
3/. ETC actuator circuit poor electrical connection.
My car has the Stillen SC kit that I think uses an extended lead to connect one of the throttle bodies, but I believe Bank-2 refers to the OEM lead.

If anyone has any info/suggestions I would love to hear them. Thanks.