About a week ago my pickup started sputtering and missing on light load after driving the vehicle for around 15-20 minutes. Replaced the Engine Heat Sensor because a mechanic friend of mine said this could cause the sputtering because of excessive fuel being fed to engine under light load. The engine runs great up to this point and even when you accelerate hard. Does anyone know what could cause this? I replaced the distributor about 4 months ago when it went out. I have currently 209,000 miles on this, but it has always been a great runner and dependable. Any help would be greatly appreciated.