its more than likeley ur head gasket buddie! no water in the oil doesnt mean a thing. whats probably happened in ur case is a water passage part of the gasket has blown and its leaking out, possibly into a cylinder aswell. check ur spark plugs for water vapour, if there is any, that will explain the rough idle.
1996 EL Fairmont - Pioneer MP3 Headunit, JBL splits, JBL 6'' 3-ways, 10'' Xplod subs, lowered, 16'' EL XR6 mags, K&N air filter, Pacemaker headers, 2.5'' Redback zorst, dba sports rotors, dark tint.
soon to come.......BA XR8