Oil pressure light blinking

Dip stick level is correct. The indicator light don't come on til car has been driven for 20 minutes. Light and alarm comes on only at a stop/idle. This was an undercover det. Car and center console was removed and light were disconnected etc. Had car for 3 years and sometimes emergency brake light comes on out if nowhere just release the brake and goes off other times will get red lighting bolt symbol or skid tracks but then goes off. So not sure what to do? Where should I start to eliminate possible problems? How do I tell if it's a sensor or a diagnosed issue? Thank you guys so much for any and all advice, Debbie