idle all over the place and smoke with a erratic power delivery

my idle on my 99 r6 wont sit still. it will go from 0.2k revs - 2.5k revs. it happens with no apparent pattern. and under heavy braking whilst ridding it tends to stall as i slow to a stop.

attempting to adjust the idle results in it going from 0.2k straight to 2.5k revs.

one thing that could have affected it was the fact that i put a race can on and used it for about 150 miles of hard ridding. but my low down power was affected so i changed back to the standard exhaust. now i get this issue which has not occurred before. i used to have the idle set at 1-1.5k revs with no issues before hand.

now the other issue, which is most likely linked, is the bluey-grey smoke and erratic power delivery. is smokes when into the 10k revs range and the power is sometimes a few seconds behind the revs. the oil light did come on while this was happening. i checked it and it was low, so i topped it up. but the problem is still occurring.

i hear that changing the end can, can sometimes affect the balance of the carbs.... or perhaps its something more sinister...

it was last serviced late november 08 and hasnt been ridden that much till now.

any help welcome.

thanks