I had the same problem and what it turned out to be was the vacuum line that controls the actuating mechanism for the intake runners was collasped. You can see wether this is your problem by looking at the vacuum pot in were the thermostat housing is and then have someone start the car and watch it to see if it actually moves the rod I dont know the tech name for the vacuum pot but if this is not working your intake runner is not opening to allow air into the engine. good luck.
