08 denali xl engine stalls after drive approx. hour cranks but wont fire

What is your question?

both times this has happened I had been driving hour to hour an a half, both times it stalled I was slowing down to stop once it was raining and cool out the other time it was at night temp was probably 70-75 degrees. Had this in at dealer no codes and of course could not get it to duplicate the problem, they did tell me the fuelpump was on the low side of acceptable range. the second time it stalled I was towing a boat drove to the lake hour drive no problem, return hour drive stopping at red light stalled, this time after cranking a few times it fired ran like crap was popping back though intake ,after engine smoothed out put it in gear was getting this clacking noise not sure trans or engine anyway made it home. drove it today I have this warning light flashing engine overheat turn off a\c temp gauge still at bottom 160 I believe is what it reads it was running and driving fine coolant level full no signs of engine over heat, both rad. hoses hot system is circuilating

What makes this problem better or worse?

hour to hour and a half of driving

How long has your 2008 GMC Yukon had this problem?

problem started a couple weeks ago