CaMmEd Ss

Ok so I'm getting ready get my car tuned, but I'm having some server issues with something pulling power. Like my gauges shut on off constantly, along with radio when my lights are on they flicker alot. I've changed my BCM (Body control Module) and still the same problem. Now when I'm on it, it won't shift right if I leave it over drive hits rev limiter when it get ready for 3 rd. Which I'm pretty sure that's tuning problem. But if any one can help please help, not looking for criticism just help! I'm in a wheelchair and I'm independent and would like take steps where I might start thanks!