When unit fires after sitting for a couple hours, the furnace makes an initial rumble and can smell oil in basement. The unit was serviced in Jan.06 for this problem and has since been fine until now. I know the service tech had changed the pilot jet (from 1.00 to.85). After unit is running for awhile and stat calls for heat,unit seems fine. Just when its' been idle for several hours, on start up, I hear the furnace shake and rumble. Please help... Thank You, B. Cannova