ok boys and girls.

today i cleaned up ALL the earth points and cables, including those on the head. they were gleaming by the time i finished!
i also checked the ecu plug and pins for signs of water damage but the pins were very clean. still, i cleaned them up anyway.
then i went to start her up:
- it turns over strongly with a slight will to start but will not fire properly (unlike last month where it would fire then die as the ignition was returned to position 2)
- if i open the throttle whilst turning it over it will occasionally
backfire 
quite loud too! but will still not start.
- the ISV is always buzzing with the ignition in position 2 (is that normal?)
- the spark plugs looks black (but not sooty) and smell of petrol
- often i cannot hear the fuel pump prime when i switch the ignition on, but i seems to prime after?
what do you guys think... is there anything else i should be looking at?
i was wondering if i should replace the HT leads, would these be causing the problem?