drive down road above 40 and put it in neutral and rev a bit and see if it goes away

 

Try higher octane gas as mentioned. Might also want to pull TB off and peek inside....

 

Still curious as to what spark plugs he's using. Could be spark knock? I have that same experience post plenum repair on my truck, that DOES go away with higher octane fuel...

 

It was the stock champions or Autolite 3923's I cant remember which I decided to go with. I put all new plugs,taylor thundervolt wires,cap, rotor, hughes plate,new bollts,new waterpump,timing chain set,rear main,oil pump,etc last year. Noise happened before and after replacing all this.

 

so the type of plugs could be causing it or do you mean the condition of them?

 

Supposedly higher temp plugs can make crazy noises.

 

I had dealings with a spark knock in my car under load and can assure this isnt anything like that..I can hear noise better if I move the shift boot. Truck doesnt act weird or spudder or anything when noise arrives. It doesnt feel like its coming from the motor at all.

 

That may be something. Pull the inspection cover off the front of tranny and check bolts to torque converter. If one of them is backed off, it could make a noise.

 

Another thing is it is loader the faster I am going. I mainly hear it on the 55 mph highway or the 75mph freeway here in az. I have heard it driving 35 or 40 or so down some roads but not as loud.

Sorry mant to say 35mph earlier not 25mph..

 

Ill do that, but if a bolt was hitting the inspection cover would it only be spinning when throttle is given and not when I am coasting at 70mph?