My 02 4.2L has been doing some questionable things lately. First off it burns a bit of oil between oil changes about a quart or two which i figure is bad rings but i have never seen blue smoke until lately when i noticed it on start up. Also under about 2000rpm there is a slight buzzing/rattle after the truck warms up or has been running awhile. This sound only happens when the truck is actually moving and wont do it if you open the throttle in the driveway. Finally my gas mileage has gone from about 19-20 to 16-17. Any ideas? anything would be appreciated.

 

Search some of my posts about rattles. You may find what you're looking for.