this is what's going on , i don't know if its normal but or if something might be wrong . i have a 2001 5.3 and that every time i start it ,it starts and idles as if it has a cam , then 5- 10 seconds later it will smooth out . is this normal with a tune ? i have a nelson tune . oh and this is with the engine hot or cold . your feed back will be vey helpful.