Need help lowering the idle when in gear.

I have 5.3 with ls1 intake and injectors, truck MAF, and truck throttle body.
The stock truck tune is fine on idle and in gear idle but somewhat sluggish and transmission
sometimes slipping. When I used the stock 2002 ls1 camaro bin it wont start. So I copy the truck maf, idle and the injectors and it start, idle 580-650rpm and runs much better than the truck bin. But the problem is when in gear the idle surges between 700-850rpm the car will run 25-35mph without touching the pedal.