The re-flash made my hanging idle worse.Personally, I'd be suspicious of a poorly set TPS. These are not adjustable and are set by airflow when made at supplier. If this isn't done correctly, and it wasn't on the 800's, it will be a potential problem IMO. If it reads low at idle, it may reduce fuel flow enough to cause this. The reflash might be making this worse.
A Bully Dog GT gauge displaying throttle percent and an O2 sensor being monitored while running a good one versus a bad one should help determine this.