Plenum leak?

[goodtodoo]

How do I tell if I have a leak?

 

[Yeret]

Oil level drops over time (I was going through half a quart per week when mine was shot)

Engine knocks under load.

Oil puddle sitting in the pan (it is said that the PCV can dump some oil here, but after my plenum repair and a new PCV valve, my pan's dry as a bone).

Exhaust burps oil smoke at startup (mine used to spit out embarrassingly large clouds).

Various misfire codes.

Spark plugs look like this...

http://www.f150forum.com/attachment...fouled-spark-plug-what-does-mean-pict0003.jpg

Every single one of mine did and I wouldn't make it a year between changes before misfires would start setting in.