I did a tune up on my stang and now I'm getting worse MPG than before I change the plugs, wires, and air filter. I'm getting like 50 miles less on a tank of gas and with gas prices this is killing me! Does anyone know what it could be?
Check the routing on the spark plug wires. Did you follow the factory routing including stand offs and loams? Run the car in a totally dark location. Look for the blue hue of arcing.
Check for vacuum leaks.
Any exhaust leaks?
Did you clean the MAF? Use only a product designed for the job. No brake clean. No carb/choke cleaner.