weird noise coming from my 89 240 please help!

[driftiteasy0113]

OK,whenever i start up my car in the morn and when its been sitting there for a little while it makes this weird almost chattering type noise,it happens when im coming down from high rpm's as well.i though maybe not enough oil was getting to my head so i replaced my oil pump but it still does it.i have no idea what it is??any help would be appriciated

[Fla240sx]

could be stuck lifters, search about it I don't know too much about it though so don't hold me to it