I am getting hesitation and then surging from my 302 110,000 miles. I replaced the egr and O2 sensor, and it ran beautiful for 1,000 miles. Not one single incident. Now it is doing it again. I have checked every hose for an air leak and have found none. I did find a small leak in the water line that runs from the thermostat housing to the throttle butterfly housing (what is that line anyway?) Could this be the problem?

 

what year? also I would check the wiring to the 02's... there may be more than one 02 sensor...