Ok I have a strange problem that has me stumped. I have a 2011 Chevy Colorado with 78,000 miles on it. This only happens when the truck sits for 6 to 8 hours. I start it up and it fires up right away no problem. It runs at 1000 rpms for 30 or 45 seconds. kind of the choke mode. it then drops to around 800rpms 3 seconds later it sputters and almost dies. it does this 3 times in a 30 second period then goes back to normal rpms and runs great! I'm getting 26 mpg it is the 2.9L 4 cylinder fuel injected engine. and its throwing no trouble codes? Its so weird you could probably use a stopwatch and get the same time every time? I have changed spark plugs, cleaned the MAF sensor, cleaned the throttle body, tried a better gasoline and ran seafoam through the system. The battery is strong the air filter is clean and the oil is changed regularly and I see no visible air leaks? nor do I see any fluid leaks and there is no smell of gasoline. If I rev the engine for about 2 minutes at 1500 rpms till it is slightly warm it will not sputter after that. I have looked all over the net for answers and have gotten some good ideas but I have yet to find a solution? Anyone have any ideas? anyone have this same problem? Any help would be greatly appreciated! Thank You!