Throttle dead spot

[eidolon]

My throttle seems to have an initial dead spot. The first 1cm does nothing really.
I thought that it was just the famous Mini hesitation so I bought a Sprint Booster which is great, it makes the throttle nice and responsive but only after you get past that first 1cm of nothingness.
I've recently changed the plugs, coil pack, plug leads and about a year ago I had 1320 fit one of their adjusted bypass valves, also had the throttle body thoroughly cleaned. None of which have really helped.

It's getting annoying now as trying to do hill starts without using the handbrake is tricky, it either feels like nothing is going to happen or you wheelspin, there's no happy medium, it's a jerky all or nothing experience.

I've made a video clip of what happens when I try to hold the revs at 900rpm, they fluctuate and drop to about 500rpm every few seconds. If I hold them at say 1500rpm it's fine (ie past that initial 1cm of throttle).
See youtube video for example (I promise that I'm not moving my foot, the revs do that all by themselves)

https://www.youtube.com/watch?v=DcJTGfO3-7E&list=UU_Y0XmgEdlyGfvQIEx5ABzA

Could it be the throttle position sensor(s)? Is there anything else that could be at fault?

 

[Firestar_3x]

Cable or drive by wire throttle?

It could be the contacts in the throttle pedal, had this on a VW years back, took the pedal apart, cleaned the contacts, was miles better.

 

[Scania]

Not sure if it's a cable or electronic throttle on those, my e46 had quite a noticeable dead spot like yours, I googled resetting it and the result was a very much improved action.

 

[lordrobs]

Must be drive by wire if a sprint booster is being used. If you can hook it up to something like Torque via the OBD port you can actually monitor throttle position in real time (with or without the engine running) which may help to eliminate either the TPS or throttle pedal assembly itself.

Video is private by the way.