So ive got an 05 Edge with the 3.0 automatic. I had issues before with cats but had them changed and now im dealing with chasing down the right problem. I recently changed valve cover gaskets and found a small crack in one. And i havent been able to find a replacement. However ive been having sluggish acceleration, engine will start shaking at 3000rpm and above along with what i think is burning oil because it will smoke a bit. But i haven't lost any oil. Ive checked everywhere i can think for a vaccum or exhaust leak. And its not throwing any codes. Anyone have an idea?

 

Welcome to the forum

Try a static REV test to see if the vibration is engine related
i.e. REV engine when parked above 3,000rpm to see if you get the same vibration, if not then not engine related

If so, then when engine is COLD, been off for at least 6 hours, loosen fan belt and remove it from crank pulley
Start engine, battery light will stay on, that's OK
REV engine again to 3,000+ RPM
If no vibration then one of the accessories driven by fan belt is out of balance, usually fan blade or fan clutch
If you still have vibration then could be crank pulley/harmonic balancer

You can ONLY RUN THE ENGINE for 60 seconds with no fan belt, so shut engine off after test