Idle: Clean or replace the IAC
is on, get the code or codes read.
Leak could also be PS fluid. Locate the source of the leak.
Heavy right foot, lots of idling, kills gas mileage. With that said, 100 miles of driving is not nearly enough miles to get an accurate MPG number.
05 Taurus SEL Duratec - my daily driver
04 Taurus SES Duratec - wifes car
95 Taurus GL Vulcan winter car
Toy #1 - 86 Tbird 5.0 (original owner) - LOTS of mods
Toy #2 - 88 Tbird Turbo Coupe - LOTS of mods
02 Pontiac Grand Prix GT
67 Honda 450 Super Sport - completely customized