Hi guys. I read often but I never thought there would be something I couldn't figure out on my car. I have a 2002 Dodge Neon 2.0 with 68,000 miles. I had many issues originally with the car, the transmission, the pcm module, the catalytic converter, and the engine long block were all replaced by a dodge dealership within 6 months of purchase. Since then however there have been no issues until recently. The car had been averaging between 325 and 375 miles per full fuel tank depending on how much highway driving was done. Within the last 3 weeks the fuel economy has dropped to 160 to 180 miles per full fuel tank. I took the vehicle to a family member who is also independent certified master mechanic. He ran computer diagnostics on the car and found no fault codes as well as checking the fuel tank and pump for leaks. Nothing there. I thought maybe the car had a bad sensor somewhere and was running too rich because it runs excellent, but its not blowing black smoke or showing any signs. After the car started behaving like this I had a complete tune up done and it has not improved the situation. I thought perhaps the fuel filter needed to be changed but to my knowledge it is inside and is part of the fuel tank. Good fuel economy is the only reason I bought the car and now the fuel costs are killinh me. What could this be?