1999 Mercury Marquis

Engine Performance problem
1999 Mercury Marquis V8 Two Wheel Drive Automatic 154000 miles

i have a 99 mercury grand marquis and im trying to replace a vavle cover gasket and im able to get to all but one and thats the very back one on the driver side the electrical wires are in the way so when I get a combination wrench on it it doesnt turn because its at the cover already so how do you suggest I get it off?
September 18, 2010.

Will have to remove some components before you can replace that valve cover gasket. The ignition coils need disconnected, fuel injector wiring needs disconnected, move PCV tube out of the way, remove EVAP valve, disconnect harness from the valve cover and move it out of way.

Sep 18, 2010.