For what its worth, I have a 2000 dakota with the 4.7L V8 as my DD (136K mi)and every time i change my oil in the winter i get that yellowish foam in my filler. I checked out the dakota forums and read many threads indicating that this was common at least for the early 4.7L's due to condensation from different cooling rates of the block and the location of the filler tube. I tried replacing my pcv valve and was almost ready to tear into the intake manifold gasket before i found that on the dakota forum. I have noticed it in mine since about 90K (i bough the truck with 80 K and didnt drive much the first winter). I just clean out the orange sludge as good as i can with every oil change.
edit: I only seem to notice it in the winter
1993 ZJ 4.0L AX-15 2" BB Rola Roof Rack, Warn 8274, 235/75/R15 BFG AT's, that's about all for now...