2 dead Cylinders?

[99MBSport]

A friend has a 2000 explorer V6 that appears to be running on 4 cylinders. Is there a common problem here, or can someone give me a n idea of what the problem could be? No Diag codes yet. Thanks

[rhandwor]

Look for a bad injector or a bad spark plug. If it has a coil on plug possibly a couple of bad coils.

[shorod]

Is it just running rough, or have you actually determined that 2 cylinders are not firing? If just running rough, then check for vacuum leaks around the intake manifold as well as making sure all hoses and intake air tubing is connected and in good shape.

Did the roughness occur shortly after something was done under the hood?

-Rod