When I am about to come to a stop it feels as if something is disengaging or as if the car came out of drive and popped into neural and wants to roll faster, so I apply the brake a bit more to stop. It is a weird feeling, I believe it is rolling too slow at this point to be the feeling of shifting into first. Otherwise the car shifts perfectly, has no ses light, codes or abnormal noises. I thought I remember noticing it after my last dynotune for the converter but it was a long tine ago and 3 hours away which I can't say it with certainty. I don't think it is mechanical but I am not a mechanic. Is there a sensor or something in the tune which could cause this? I can't imagine it is a normal characteristic. Thanks for listening, any suggestions guys?

Only mods are the 3200 278 Circle D stall, 342 gears catback & the tune.
Also it is doing the same thing before and after a new balanced driveshaft w/ yolks, trans mount, posi unit and axles.