We (I) got sidetracked about sand

but what air filter do you run? Can you post a pic of it? I really don't think that's your issue but it's hard to rule things out w/o actually being there to diagnose- although this forum has some excellent resources!!
Already mentioned: compression check. What does the receipt say was done by the last guy? I'd fight the guy for a few bucks so you can take it somewhere else. Does he have a website or FB page? How long has it been? I know that a couple crate motor outfits have excellent warranties. Ford Motorsports does not.
Otherwise, buy a good Bronco specific cover and take that beautiful looking EB you have to a reputable shop. Make SURE you have your insurance up to snuff and the shop is reputable.
Keep us updated. Best of luck