recently my glanzas engine has made a problem for its self, the idle is rising and droping, it drops to nearly stalling out then goes back up to over 1000 rpm i have cleaned the idle control valve and swaped all the plugs over to see if it makes a difference but its just the same. it was serviced on saterday new plugs oil filter etc, when i took the plugs out the wer thick with soot and i had only covered 80miles its running rich? i think thats what it shows its forged tdo4 emanage etc anyone got an idea