I have a K1500 5.7l 4x4 suburban. The last week or so it's been idling rough, but smooths out once it warms up. Yesterday, it started rough and kept getting worse. Then my SES light started flashing. Not just on constant, but flashing. I shut it down to avoid any damage (hopefully). I should also mention that I replaced the thermostat about a month ago. I've been trying to get all the air out of the cooling system, but still get some gurgles in the overflow tank when I shut down. When the stat went bad, it got up to about 240 on the guage, but I shut it down as quick as I could. I'm hoping this is a fuel issue, but afraid it's more serious. Any thoughts?