Ive had this mystery noise for at least 40K miles. On light acceleration you can hear what sounds like a pitted bearing or a marbly type sound. I thought maybe the timing chain /tensioner but the timing is dead on and no slack.

The truck runs great. Ive done a lot of work to it and maintain it as it should be. 135K miles, purrs, full power and amazingly smooth idle at a stop. You cant hardly feel her running. Its just this noise that is evadiing me. Someone once suggested it was the PCV valve hammering, put a new one on. No such luck.

Any clues?

Oh the only driveability issue I have is when its first started for the day. Idling I get an intermittent miss but it goes away and as I stated above, runs like a top. Changed the coil pack, distributor, wires, plugs, intake gasket last year. Every 5th tankful I run injector cleaner.