Runs sloppy after trying to restart hot engine

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I am a rural mail carrier and about 2 hours into my route I have a place where I have to stop and turn off my Jeep, when I get back in to start it will barely run, it sputters, dies sometimes and sometimes backfires it takes a couple of minutes to get over this fit but then it runs just fine. One time it threw a code 3rd cylinder misfire, I changed the plugs etc and still have problems. Lately, it don't throw the check engine light. Any ideas what this could be, about to drive my mechanic nuts, he used to work for a Jeep Dealer.