my crown victoria is showing p0108 and I changed the mass air flow sensor and gas cap do u think it could be the pcv valve or the egr valve
That code for Ford is not exactly the same as the generic equivalent:
P0108 - Ford Type Powertrain - Fuel and Air Metering - ISO/SAE Controlled Description
Barometric Sensor High Conditions Cause
Engine running and the PCM detected a BARO sensor operating range of more than 5.0v
P0108 is the DTC for MAP circuit high. This means you have either a faulty MAP sensor, usually part of the engine ECU in later vehicles, or you have low manifold vacuum. This can be caused by incorrect cam shaft timing (new belt lately?), valves adjusted incorrectly, or a simple air leak on the engine some where.