I have a 99 GMC Suburban w/ a 5.7L engine that I have been having issues with trying to start. When I first try to start it, it cranks, but doesnt start. If I stop cranking it for a few seconds and turn it over again, it starts after a few cranks. Once it's started, a burnt smell comes into the passenger area from the vents (obviously from under the hood).
Now, I went to start it the other day, and it wouldn't turn over at all. In fact, now it cranks for a second, totally stops (like there is no current) and then cranks again, all without letting off of the key. Unfortunately, I haven'e been able to get it started yet.

Can anyone please give an idea what this sounds might be the problem?

I did get a code a few months back of a multiple cylinder misfire if that helps...