You left way too much out, I know you think you went into great detail but you didn't give any timeline for when things were acting up, when they cleared, etc.

My only comment is this: You imply the car runs fine but the instrument panel and spoiler are going nuts. The most common cause for either is a bad battery or heavy corrosion on the battery cables, terminals, ground lug, etc.

I'd inspect the battery terminals, ground cable lug, etc. If I could find no obvious problms, I'd replace the battery and go from there.