I am having trouble find an upper intake plenum OHC 4.0 for my 1998 ford explorer. Does anyone know where to get one.

Welcome to the forum!

Where have you looked? Have you tried a salvage yard, engine rebuilder shop, and dealership? What about eBay, there are often folks parting out their Explorers.

-Rod

I sell thousands of explorer parts on ebay....usually 95-01 right now.....ebay name is automotive_unlimited....I have a plenum from a 99 OHV...still installed if that'll work for you...my phone is 1-740-596-2077 name is Tom