Loss of power and rough idle.
Yesterday, after a 1 hr drive and 1 hr rest, heard a tic-tic-tic sound and had an immediate loss of power upon restart. The truck started shuddering and continued loss of power (not achieving rpm of more than 2200). Very small puffs of white smoke from exhaust only when reving engine, but idling fine with no smoke. After sitting for 4 hrs - ran fine for return trip home. Today, ran fine in town, but did the same loss of power and smoke after sitting at an idle for @ 45min and now has a rough idle. Went to restart after a few hours and has not improved this time. Not leaking oil. Any thoughts?