Engine Performance problem
2005 Chevy Cobalt 4 cyl Front Wheel Drive Automatic 77000 miles
I changed my air filter and gave my car a tune up. My car starts out great but about 15 minutes after running, it starts to bog and feel like it wants to stall. It had stalled on me twice though already. I did a read with one of those devices that connect to the computer to get codes but it came out ok. I am getting gas, but it feels more like air problem or something. A couple of times I had take my foot off the gas and brake and it would go and stop in spurts and you can see my rpm go from 0 to 15 rpms and the car keeps jolting forward without me stepping on the gas. I tried to reset the computer by disconnecting the battery cable and I also used fuel injector cleaner because I thought it was fuel injector related at first. Any suggestions? Thank you for your time.