Truck surges when idling

Try cleaning throttle plate on both sides and IAC hole with choke cleaner.

So you mean by surging, rpm's up and down, like its hunting for the correct idle? If that is the case it does sound like a vacuum leak. This would be suspect also because you have such low mileage and the vehicle is older. Gaskets harden up after sitting for so long. Have you tried using starter fluid and spraying it lightly around the intake manifold gasket, throttle body, valve cover gaskets? Any place that air could be getting in. Just be very careful spraying fluid around any hot parts of the engine. This is a very good way to locate a vacuum leak. If there is any change in rpm's that is where your vacuum leak is. Usually a hunting rpm's is the result of a leak like that. Also is the check light on and has it been scanned for codes recently? Even if the light is not on there may be a code stored in the ECM. You may want to have a fuel pressure test done to make sure everything is within specs.