I have an 86 Wagoneer limited 2.8L V6. When I shut it down, it sounds like a disel engine. I need some input???

 

its actually called "dieseling" its when the engine keeps running due to the conditions in the combustion chamber causing ignition of the gasoline.

Im not too familiar with the early V6 XJ's, but my first instinct is that your FI is not shutting down like its supposed to.

some vehicles have an anti-dieseling device, might look into that

 

What's your idle speed like? Sometimes if it's set too high it can produce the dieseling.