When starting truck in cold tempatures rpms start at 1500. After about 3 seconds they move to 1000 to 900. After another 2 seconds down to 700 to 800 then truck shakes alot, sputters, really rough and almost sounds like its going to die. After 10 seconds of that the rpms stay the same or go down alittle but the roughness and sputtering goes away after the engine has warmed up obviously. I have had this problem the last 2 years but keeps getting worse every winter ( minnesota). I have changed the fuel pressure regulator the last 2 years, plugs and wires done around 60,000 miles ( truck currently is at 84,000 miles). Need help not to get screwed by auto business. Any advice would be totally appreciated.