4 qts low... valve cover gasket?

[BIGGER]

My truck has been running rough for a week or so and was surging pretty bad this morning. I have been working so much I haven't had time to check it myself. I took it to a highly recommended shop this morning.

They called me and said that the fuel filter was dirty, OK. Then they said it was 4 qts low on oil. 4K miles since last oil change. They said the valve cover gasket on passenger side is leaking.

Is there that much oil running through the valve cover to leak 4 qts in 4k miles? I have not noticed any oil spots under the truck when parked.

I have been getting a bit of blueish color in the exhaust when I first start it. I was thinking more along the lines of injector o-rings.

Is there a way to test the injector o-rings without pulling the injectors?