2011 Chevy express 1500 cold start issue
 

When I start the express van up after sitting all nite it runs rough and kind of "pops" for a second or two then seems to run fine the rest of the day. It has 262,000 miles on it and I maintain it very well. I am self employed as a delivery driver of auto parts to Gm and ford dealers so I run about 200 miles a day weekdays. it was tuned up about a year and a half ago with plugs,wires, dist. cap and pretty sure air filter. Asked a few dealers what it might be and got several different answers which is understandable. I checked the air filter a little while ago and its a little dirty but I dont think bad enough to be a problem. I knocked the dust out of it and put it back in and checked it cold and same problem. I can easily get a new one tomorrow and install it but dont think it the problem.
Talked to couple other drivers and they mentioned injectors.
I thought maybe that also and asked if injector cleaner would be worth a shot but they said no.
My question is should I try the cleaner? will it make things worse?
Any input appreciated.

"Kind of "pops" - can you try to explain better what your problem is?

I'll try to explain it better. Sometimes,but not always it sounds like a small backfire. Like maybe the engine was flooded and its trying to burn that extra fuel off. Other times it sounds like its not running on all cylinders for a few seconds. I'm not a mechanic so I'm sure my description makes it confusing. It only lasts for a few seconds and then runs ok the rest of the day.