truck sounds weird

[bigchevyc30]

im wanting top know what would a gas motor sound like if there was diesel in the tank as i filled up today and went to help my brother the truck sounded fine then but when i got home it has a really odd sound and was idling really low. truck seemed to have a sputter to it but i let it sit for a few minutes and cranked it back up and it sounded normal. would anyone know why it would sound like that

[bake74]

     Not diesel.  If you put enough diesel in a gas engine it will lock up, and if it does not lock up it will bang and clunk something fierce.
     Diesel fuel takes a much higher compression to ignite.  Odd sound like vacuum leak would make,  which could be why it is idling low.  Your fuel filter is not dirty is it ?  Filters can start to plug up, when ran long enough they reduce flow, let it stand for awhile it clears up a little until you run it again and it restricts again. 
     Need a little more on what it sounded like.

[bigchevyc30]

its is most defiantly not a vacuum leak it has a rasp to it when it idles but i defiantly know its not normal at all. it to me i think sounds like it has a miss in multiple cylinders or something but ill find out in the morning when me and my friend look at it as it was dark when we got home

[bake74]

     If it sounds like a few of the cylinders are missing, check your Dist. under the cap and see if it is all clean.  Maybe some got a little corrosion on the brass connectors under the cap, just enough to make a couple of them miss.