Q: Rpm going really high and mph going slowly

It sounds like your vehicle’s transmission is not shifting properly. Check the level of transmission and fluid condition. If the fluid level is low, that will cause shift difficulties. If the fluid is discolored or has a burnt odor, that would reflect an internal mechanical fault. Failures to shift are due to either external control failures, including in some cases engine related controls such as the throttle position sensor, but also including the vehicle speed sensor, transmission control module, and shift solenoids. Many of these issues can be repaired with the transmission in situ. Internal faults can be due to valve body faults, plugged transmission filter and failed piston seals, o-rings, bands, and clutch packs. To identify the problem, the recommended service is a failure to shift diagnostic. Once that diagnostic is complete, the mechanic will explain the repair strategy to you in detail and estimate the cost.