I have a 2006 4.7 HO, 5 sp auto, 4X4 Dakota with about 76k miles. Recently, even with the hot weather, I've noticed the idle speed surging when first started on a cold start. I say cold start but it's actually about 75 deg. ambient or higher. The idle speed will surge to about 1500 RPM down to 700 or 800 then back up and back down about 3 or 4 times before settling in at what looks like about 700. Once I put it in gear and drive off everything is fine. Subsequent warm engine starts through the day are fine. Is this a sign of something or not a concern? No codes and the truck runs like a top.