1988 Ford F-150 What is the filter inside intake manifold un

I just purchased a 1988 F150 and am tuning it up and there is a very small rectangular filter underneath the air filter in the intake manifold. It connects to a hose running back near the oil filler hole. I have checked my alldata manual, my haynes and can not find mention of this. A universal car manual I have indicates that it is the pcv air filter. It is very dirty and I want to replace it but can't find this part listed online and ford's parts catalog just keeps giving me pcv valves. Is this filter the pcv and if so how do I find this part - is there another name it might be listed under or has it been replaced with something else? Also, the filter shows signs of oil, does this indicate the pcv valve might need replaced? I can provide a picture if needed. Thank you!