Another Popping noise

Problems never end for me it seems. I'm getting this popping noise from the front end of my 89' xj. It happens when I drive straight. Its like individual little pops. I can get alot in a few seconds or I'll get one then 30 seconds get another pop. Sometime it pops hard some times it pops soft. when it pops though, ofter time it pulls my steering to the left.
Any Ideas? I'd really like to get this taken care of. Its driving my CRAZY!
I did alot of searching, but none had the poping in 2wd or while driving straight.
-Matt