Spray all vacuum lines and fittings with carburetor cleaner with the engine running. Listen and feel for the idle to smooth out or get rougher. Also, spray around the intake manifold to cylinder head mating surfaces and the whole intake manifold. This will check for vacuum leaks. Disconnect the manifold absolute pressure sensor on the intake manifold to see if that clears anything up.
Try changing up where you get gas, this will eliminate the quality of the gas as the culprit. Run a bottle of injector cleaner through the fuel system to see if that clears up the problem, though I doubt it will.
You may also have a fuel tank that has contaminants in it that are being picked up by the fuel pickup immediately following a fill up. Lower the tank, remove the pump/pickup assembly and see if the filter screen has pieces of rust or metal in it. Filter the fuel into a clean gas can and clean the tank out if so.
Tuesday, June 7th, 2011 AT 7:44 PM