gas gauge and engine temp gauge not working and speedometer not working all the

Sounds like something instrumentation related. You can't really be sure unless you perform related testing in the circuit to and from the cluster. I'm sorry, but I'll definitely say Mercedes-Benz experience counts here. Looking at the wiring diagram alone takes some expert experience. I'd say logically that multiple cluster gauges not working right would be some kind of power problem. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops