Hello and welcome to Just Answer. I will try and assist you with your problem.
I think you are on the right track. Chevrolet had a big problem with these injectors that's why they extended the warranty. It is now 200,000 miles or 7 years (what ever comes first) so you are out of the warranty by time.
It sound like you are at the beginning stages of it. It usually is accompanied by a check engine light, hard/no start, Rough running. What happens is that the tips of the injectors crack (a piece could eventually brake off) and they will dump excess fuel into the cylinder. One thing you can watch for is your oil level and the presence of fuel in the oil. The only way to diagnose one in early stages is with a factory scanner or one that is capable of factory bi-directional controls to see if it can not achieve high fuel pressure. I hate to be the barer of bad news but at least you should still have a little time.
Check engine light has been on and off for last year. Had it checked by chev. dealer just before they went out of business. They said it was a glow plug problem. That my be with an injector problem on top of that. Has been a bad year for my chevy. Transfer case clip rattled a hole in the case and cost me big time. Then the pump in the transmission went out and along with new torque converter another bid deal. Has chevy helped any of these injector problems with any kind of discount on the parts? I am about 100 % sure of that answer.