Ok, guys, I've been monkeying around the web trying to find possibilities to the problem, so I thought I'd end up asking you all.
06 Cobalt with a 2.4 auto. Upon acceleration, when I give it gas, the motor bogs down for a second or two before it kicks in. It feels like the response time should be quicker. It gets up to highway speed but when I try to pass it gives me some hesitation before going. No CEL's, idles fine, and recently changed out the plugs and coils. Fuel and air filter were just changed and oil was just changed. I'm also getting 24 mpg at best on highway.
I know it's just a 2.4, but still seems too sluggish.

 

You have done most everything needed for a good tune up.

Maybe try a good fuel system cleaner for a couple tanks of gas.

Have you ever cleaned your throttle body?

What spark plugs did you use? What coils did you use? You should generally replace with only ACDelco parts Especially the coil packs

 

Thanks for the reply. I plan on doing the throttle body this weekend, along with checking the tranny fluid level, and doing a vacuum test to check for restrictions.
I used NGK Iridium plugs and Denso coils.
What's the best fuel system cleaner to use?

 

Just make sure when you clean the throttle body do not move the butterfly just spray it with cleaner and leave it be