serious drop in rpm at a stop light 95 gt

[vicma762004]

last night after i left work i was coming to a stop light and bammm the rpm went from 1500 to like 400 real fast and surged back and forth for a bit then it settled into place. this all happened about a block away from where i work so had just started the car after 10 hrs at work. i kindda freaked out and i was wondering if this had happened to anyone else.

 

[Bosko5.0]

have you had a tune. I was tweecing myne and it was doing the same but it would die I guess until the O2s heat up.