so every time i go out and push my car or accelrate...it used to be more responsive so im like somtin is rong with the spark......i took out the sparks i could the first one and the one closest to the windsheild and they were pretty OILY and dirty.....and in the middle part where all the spark plugs go..i have old oil all crusty and old layin there....also smoke comes out form the front of the valve cover or right behind the thermostat housing on the block....what could be the problem???? the smoke only come sout when i push the car harder than normal driving and when its at normal temps.....my car is stock...also it blows a bit of smoke when i start it up...any one know what i should do to fix this??? thanks in advance