Blip - a quick throttle opening (short vrum) whist the clutch is pulled in and shifting (esp down). It's habit borne of older vehicles that needed double de clutching to change gear. Especially if they have BIG HEAVY flywheels.
500-600 is LOW - and my guess is the beastie's TIGHT. Mine did the same in gear, clutch pulled in when it was newer esp with the secondaries at 100%.
What does it idle at in "N"? The idle values are set in the ECU - But afaik only are any use in "N".
Has it stalled in gear and pulling? - if not PERSONALLY I doubt it's an intermittent wire contact. Vibration would set it off.
Looms = harness, yes.
