Im getting E-30 = RPM OUT OF RANGE .and F-40 = AIR MIX DOOR PROBLEM.

Hello, You likely have an issue with the engine speed sensor(if equipped), crankshaft position sensor, or camshaft position sensor. These sensors provide reference data to the engine control module for comparison. When the ECM compares the data, it must find them all to be matching at all engine speeds, and if not, E-30 will be displayed. This could be a combination of other issues, like the transmission input speed or output speed sensor, so testing is highly recommended.