Had a strange idle sound...

[Mishka]

So strange thing happened, drove truck a lot today, let it sit for few hours, drove about 4 miles to Walmart (started right up like always) and truck sounded bad when I parked.... drove like always but sounded really bad when parked and sounded Normal again after coming back out of store and when we got back home.

Think it could bad fuel?? Maybe a sign injectors are going?

 

[riphip]

Get some Hotshot Diesel Extreme and pour in both tanks. 1/2 in each tank.

 

[MtnHaul]

Assuming you have a functioning tachometer, was it steady or fluctuating?

I second the HotShot or similar product. You could also try filling a fresh fuel filter with ATF and let it run long enough to fill the IP and then let sit overnight.

Hope it's an easy fix!