Slice each jalapeno open lengthwise, then make a small crosswise cut at the stem end to form a T. Gently open the jalapenos and scrape out the seeds and membranes with a knife. Put the jalapenos, milk and 2 cups water in a large bowl and soak 15 minutes, stirring once or twice.
Meanwhile, mix the cheddar, cream cheese, pulled pork and chili powder in a bowl with your hands until combined. Drain the jalapenos and pat them dry. Stuff 1 to 2 tablespoons cheese filling into each pepper.
Put the flour in a shallow dish. Whisk the eggs and 1/2 teaspoon salt in another dish. Put the breadcrumbs in a third dish. One at a time, hold the peppers by the stems and dredge in flour, then dip in the beaten eggs, letting the excess drip off, and roll in the breadcrumbs; dip in the eggs again and reroll in breadcrumbs. Transfer to a plate and refrigerate until the coating sets, about 20 minutes.
Heat about 1 inch of vegetable oil in a large saucepan over medium heat until a deep-fry thermometer registers 300 degrees F. Fry the jalapenos in batches, turning, until golden brown, 4 to 5 minutes per batch. Drain on paper towels. Sprinkle with salt and serve with barbecue sauce.