Todays the first day taking out the new(to me) RX.
The mods are turbonetics t-62, PFC, and other supporting mods.
At the traffic light, randomly, the car would surge usually from 1400 RPM to 1900. I did notice that it was in gear when it would do this. So I would put it into neutral and release the clutch and it would settle down to about 1300. Sometime it wouldn't help at all though. Any help is greatly appreciated.

Thanks

 

If the pfc is new then check and make sure it is installed correctly. My car did this for a while and it turned out to be 3 wires needed to be clipped and voila... no more surging idle.. OF COARSE this is after making sure you have no boost/vac leaks and the TPS is set correctly. Do a search on here and you should be able to find the wires I am talking about.

edit** here is the link to those wires. http://westpenn.rx-7.org/ApexiPFCpinout.htm
I bought the car used and the previous owner neglected to clips these...

 

Thanks, that may very well be what i'm looking for. I'll check in the morning.

 

also make sure the 02 sensor feedback is turned off..

 

So after spending the day trying to fix my idle surging, I've noticed that it only surges when the radiator fans are not spinning. As soon as the fans come on, it stops surging. Why is this?