engine light issue

[SLOW_V]

I was driving my '90 laser rst yesterday during the afternoon rush hour. When I was slowing down my check engine light will flicker on. Then about 5-6 secs later flicks off each time there will be a clicking sound behind from the radio. At the same time my radio's volume will cut off but the radio itself would stay on. This happened pretty often during the 25miles hike home. Does any ever experience this? And what could be a solution? I am thinking I have a grounding issue some where.