PCM ground issues?

What is your question?

I have a 01 Deville that when I hit about 40 mph or go down a bumpy road the speedometer goes crazy and car dose not want to shift it poped up on the dash service electrical system. Then about 2 weeks ago it got real bad poped up service Trang and it was shifting hard. I think it's the pcm ground but I'm not sure and I don't know how to find it if it is

How long has your 2001 Cadillac DeVille had this problem?

A month