Changed carb, still having issues, diagnostics?

[benbloom]

hey all, i replaced my carburetor to try and solve backfiring through the carb and rough idle. with a new carb, and gave it a tune up , same issues keep happening. i suspect now that its something bigger and more serious going on inside the engine.

truck is burping black smoke out of the exhaust
backfiring through carb
idles very rough

anyone have any ideas? should i just have a mechanic look at it? i get this feeling like I'm going to be looking at a rebuild or crate engine