On the highway I can hear a slight rattling noise. It depends on how much throttle I use. I usually go about 60 mph. I use about 5-10% throttle and I don't hear the noise. About 10-15% throttle (speed up slowly) I can hear the rattling noise but if I give it a bit more throttle (~20% and higher throttle) it goes away. I don't hear it under quick acceleration, usually under slight acceleration. It almost sounds like a belt but there brand new and tight. Timing is at 5 degrees and I use 87 octane. Motor has 116k. New plus, wires, fuel filter, injectors, cap, rotor. I'm suspecting timing chain?

Thanks

 

Ain't no belt involved. Best you pop off the valve cover soonest and take a look. You may see two grooves in the driver side of the engine timing cover, and some missing pieces of plastic chain guide. I did mine at 150,000 miles without having to disturb the cylinder head/gasket or oil pan/gasket. Pieces are somewhere down below , but they don't float; and I don't worry...good luck

 

Are you getting any rattle noise at startup? (When my drivers side chain guide broke, I got a rattle a first startup for a second)

 

When mine went, the startup noise like Paul said was a big indicator, and when letting off the accelerator the chain gets slack and slaps against the side. I found it to be quite a distinctive "slap" sound, as opposed to say the "tap" of valve clearances being out.

Definitely take the valve cover off and take a look, it's a quick way to confirm, and you can always check your valve clearances while you're in there!

 

Exhaust, timing chain, or connecting rods. These are the most likely candidates each require various degrees of concern

All respond to throttle and engine load and can be tracked down with your mechanics stethoscope.

 

Sometimes I hear a light tapping noise when it's first started but it goes away after about 10 minutes of driving. It's weird because it only does that every once in a while. Sometimes the truck also runs a little rough after it's started warm, I don't know if the timing chain has anything to do with that either?