Three very bad spark plugs

On my 92' S15 Jimmy (4.3 W) I changed my sparkplugs and found that on passenger side the plugs had regular wear minus the carbon buildup from the egr problem (fixed) But on the driver side the plugs were ashy white as if they were fouled out- my question - Is there a reason that ALL THREE on driver side look that way? why would all three injectors be bad simultaneously?

check for an intake gasket leak on the left bank. try spraying some carb cleaner or wd-40 around the intake while running if you find a leak the engine speed will change. also check the oxygen sensors.