I have had some rough idling lately but my RPM's haven't changed at all. I have replaced the fuel filter and air filter and checked for vacuum leaks. Nothing came up. My truck sounds like a diesel engine when i come to stop lights. I can't figure out if my belts are causing this or what. My gas mileage has actually gone up since i have replaced those two filters so it seems as though the engine is running good. With the truck running i popped the hood and took a listen...it seems as though all my pulley's that are holding on the belts are squeaking but i wouldn't think a squeaky pully or belt would cause rough idling. I am kinda at a lost. OH...this is on a 83' FJ60.