droning noise

I have a 98 Ford Ranger 4.0 with 88,000 miles. I installed a cold air intake on it. Now, when the outside temperature is hot, like 70 or above, and i'm idling or going at a slow speed, it drones. the sound is almost like the horn is stuck. it doesn't drone in the fall or winter, or when the heat is running. But if you run the ac, it drones constantly, even while coasting. if the stock air filter is placed back on, the sound goes away. I've used several different cold air intakes, and they all drone, so the problem is with my particular vehicle. Some people say it is the mass airflow sensor, while others say it is the throttle body. What is your opinion?