Vibrations (front end?)

[GRUZER-ED]

2005 YUKON
Intermittent vibration you can feel in the steering wheel. Comes and goes at vritually all speeds. Feels like you are driving over some fairly mild "rumble strips".
Yukon has all wheel drive.
Any ideas?

 

[Time2Kill]

Is there anything that you can do to make it start/stop or get worse/better?

My first thought would be the front axle unless you have a HORRIBLY balanced wheel or a wheel that lost a weight.

 

[GRUZER-ED]

Thanks for the reply.
No I can't seem to do anything to make it happen. It just does it randomly, but frequently.
I was told that someone else had this problem (or similar) and it was an engine sensor.
I feels like there are "rumble strips", or rough spots on the road, but ther are not.