well its not the 1st 3 as i tested that lol and im using the standard hpi g3 plug with model technics 16%.
i stripped apart the car earlier to source the problem as there was a rattle as well when the engine was going, and i noticed the clutch bell was broken (the teeth had sheered off the bell) and i now believe this to be the problem, as it was slipping causing the to run free, then as it gripped again put slight tuque on the engine, hence causing the "bob" effect and the idle.... well im hoping its a simple fix like a new clutch bell, but it needs replacing either way.
I sure hope it is that simple as i just bough all the purple hop ups available for it, a new engine would be the last thing i wanted lol
cheers for the help, any more suggestions keep them coming