What version of Haltech software are you running?
http://www.haltech.com/index.php/ecu-ma ... 9-released
Version 10>>>
Added the following advanced functions:
speed limiter
Added Idle control generic duty offset tables
Not sure it covers the pro harness, I can always download it and test it for you..
Is your decel rpm tuned or left blank? Mine is left blank which I don't think 'helps'
Decel RPM Rate - This value determines for the idle controller if the RPM is falling or steady when off the throttle. When the RPM is steady at the Start Position then it is ready to be controlled.
If this value is set too low then the small fluctuations of RPM at a steady RPM will make the controller think that the RPM is not yet stable, and the controller will not operate or may be very slow to operate. You might see the idle duty or position 'hang' at the Start Postition for an excessively long time.
If this is set too high then the RPM could be considered steady when it is still falling. This might result in the controller starting too early which will cause the duty cycle to fall drastically to try and slow the engine speed when the engine is already decelerating at the fastest rate that is mechannically possible. This may cause a dip in RPM before settling on the Target RPM.
^ which in turn can stall the engine, try the AC stuck on (that'll increase the low idle)
Are the lower tables C?'d (copied through to the OEM ECU), not sure that's advisable with aftermarket (bigger injectors then 440cc)