Unstable Idle On Cold Starts

[netdude]

hi! i am having a weird problem with unstable idle on cold starts. it's weird.. here goes:

when i start my car cold... the idle freaks out a bit and jumps around between 500rpm and 1200... this only goes on for about 10 seconds (if that) and it eventually goes to around 800 or so.

however, if i spray WD40 on the throttle body... it starts up perfectly... well, it starts at about 1000 or so, and slowly (within 5 seconds) drops to 800 and stays stable there.

So... my solution so far is to spary wd40 every weekend or start the car and hold on the gas for a second and slowly manually drop the idle.

Any suggestions? Anyone with a better idea for a lubricant? I hear WD40 attracts dust so that's probably not the greatest lubricant for the throttle body.

Any help would be greatly appreciated. Thanks a million.