Alot of clattering in the engine like the valves.

Alot of clattering in the engine like the valves have to be adjusted proper. The oil is fine and full. My question is could there be an exhaust leak and how could I find it easily? The noise is mostly when pulling away from a stop, when the truck is under load. At idle it still clatters a little. The engine is a 5.8 EFI. Could the noise also be the main bearing between the motor and tranny? How would I check that out?