check engine codes

so my car starts when it wants to on park ,but always starts on neutral and sometimes the shifter does not lock in park(AUTO)..I also have a funny idle while i am driving and the needle reaches about 2k and it goes up and down between 1500-2000k for a few seconds and then it leaves(when the tranny down shifts)..so today i was driving the p5 and the cel came up..i checked the codes and this is what came up

1.P0705 (Transmission Range Sensor Circuit(PRNDL Input)
2.P0090 (Fuel Pressure Regulator Control Circuit)

Questions:do i have to swap my entire shifter box since the switch seems to be all connected or is the switch located somewhere else? Is my fuel pressure regulator bad or its something else?

i was told that the transmission range sensor is on the tranny where the cables go and that the fpr control circuit is the black solenoid looking part with the vacuum lines,,is this correct???

any pictures or ideas on what i am supposed to change out guys??