idle issues

[1973dusterkid]

Ok so I have my car idling at about 850 and it runs and drives fine but after driving it for a few mins when you stop at a red light of stop sign it idles at about 1300 what is causing it to do this.

Info

360
4 speed
750 holley DP ele chock vac sec

 

[TrailBeast]

Timing off, running rich, worn throttle plate shaft, insuficient fuel burn from overall tuning.

Then theres the not so normal stuff, but start with a good chk of these comon things.

 

[1973dusterkid]

Thanks