Backfire?

[72cut]

So just started my 88 in order to move it, was idling pretty high. I heard what is best described as a backfire didn't think anything of it. When I went to back of vehicle i saw large amount of soot/carbon under the tailpipe as well as spread out across my garage floor about 4-5 feet. Truck seemed to not idle as high. Cause? Good thing? Bad thing? Neither? Thanks

[Eagle]

Could have been a mouse nest in the tailpipe.

 

[cruiser54]

Ah, yes. Projectile mice!!

[pizzaman09]

Mine will backfire every once in a while if I am running it hard and change gear after being up over 4-4.5k rpm.