i've removed the battery waited etc connected..
this seems to have improved idling. car sets the idle speed better when ac on ac off on gear etc.. yet this has been on and off before so i don't think it will be a solution but yet to be seen.

ensoniq5 thank you for the TPS suggestion, i've learnt something new.
i googled around and learnt how to test it, so using a voltmeter i checked the voltages. at this stage i noticed the throttle position screw (not sure what it's called) i tightened before to prevent the engine stalling was slightly high and caused TPS to fluctuate voltage when tapped on it. the voltage became stable once i loosened the screw at 0.62 which seems slightly low if what i googled is accurate. i've read people suggesting 17% of default 5volt line i guess comes around 0.8 volts or near.
apart from that TPS seems to operate smoothly up and down and doesn't fluctuate when rattled or tapped on.
while at it i also cleaned the connector plug.

it looks good now, but as mentioned before car does this on and off for no apparent reason. i will monitor and report back. in the meantime any other information about possible causes is most appreciated.