Idle & ignition timing

[Matteo91]

Hi everyone, I have a range rgover classic with 3.9 v8 rebuilt with a kent cam h 180 ... new oem stepper motor and I have no air leaks in the plenum chamber, rover pressure gauge has no fault code, my problem is in the gear shift, when the clutch is released with little gas the engine accelerates revolutions per minute 1200-1500, or stopping at an intersection before descending to 700 rpm takes about 3 seconds. I have setting the idle but i have a small difference... i have setting high timing ignotion 19° i think is the causes.... whow do you think?

[100SRV]

Is the road speed sensor working correctly?