MARK3 ,sometimes hard to start, idle rpm not stable.

[chinesedawn]

I adjust the timing today, but I adjust the timing at 860 rpm not 700 rpm( it is the lowest rpm) , the engine runs really good now ,idle rpm stable at 1000 rpm, but I get a new DTC.....Which is #51( Switch Signal, No "IDL" signal, "NSW" signal or "A/C" signal to ECU, during diagnosis check )

No code Yesterday but #51 DTC show up today when I start the car. You said no code can be present when adjust the timing so I don't know if is OK or I should find out what is the problem and how can I do the Diagnosis.

Oh yeah other than this, my car's gas pedal has about half inch free play and not very sensitive, always take about half second to raise the RPM after I depress the gas pedal, is this normal?