i am having two issues. the main is a semi rough idle/accel, and coolant leak

What is your question?

the rough idle is from start to warmed up. when accelerating it surges? unless floored. recently it developed a large coolant leak. i cant tell exactly where its coming from be it seems to be from behind the water pumps pulley. the surge has been there since i bought the car. has 243k miles. 3.1 v6 chevy lumina euro. got map and maf codes saying bad compression or bad reading. vague code.