Why does my 305 tbi idle so high???!!!

[TruAggression]

On my 87 its got the stock 305 tbi in it, I've replaced pretty much everything sensor related on it including the throttle body base gasket and it still idles at about 1700 when I first start it up and stays there for at least 10 minutes or so then slowly goes down to about 1200 when its all warmed up could it be timing? Theres no check engine lights on, its just getting on my nerves and wondering if anybody else had this problem on a tbi motor. If anybody can chime in and let me know what to look to do that'd be awesome.