2.3 sticking valves?

I have a 97 ranger with sticking valves. when i start it cold it cranks like out of time in the valves, like no compression in a couple cylinders. but will start and run on 1 or 2 cylinders. but after a minute or less of running it picks up the other cylinders and then runs fine till it sits and cools off like overnight. then it will do the same thing again. . will an oil additive help this, anyone else ever had this problem with there ranger?