sprayed5oh

I have a 95 z28,I unhooked the battery to install some batt terminals,stereo and amp at work,pulled out of work and i go to stop at a red traffic light and the tach will drop to 400-500 rpm about 5-10sec and then kick back up to normal 800-900rpm.Every time i come to a stop or slow down with the clutch in it will do this.Does the computer have to "relearn" its self and how long does it take?I drove the car for 40 miles in the past two days and still didnt help.The car is tuned with lt1 edit,did unhooking the battery erase the tune? or what could be causing this? thanks
Also i should add the car has a hotcam with full bolt ons

sprayed5oh

anyone know where i can download free code scanner to check for codes?i have a akm cable,but the ses light i not on.

BRDAPRAY

sounds like a vacumm issue. I would look for a leak.