2013 Suburban LT, no CEL, no other warning lights.

I've felt like the bus is running sluggish, struggles to get around traffic in the the passing zone (60-80), struggles to get up a hill, etc. Took it out yesterday, floored it, 0-60 in 14 seconds. From what I've read, that should be 7-9 seconds, depending on the source. Same powertrain as the Tahoe and the HP uses that for patrol...this definitely isn't running like something that could chase someone down on the highway. Changed the air filter the other day, cleaned the MAF sensor, haven't quite made it to the throttle body yet, but that's next.

Am I wrong, these should be faster than this, right? I know it weighs 3 tons but still... Bought this for a road trip vehicle, but wouldn't mind putting a camper or boat behind it on the odd occasion, thing doesn't feel like it would pull that.

I have an old code reader, haven't tried it since the CEL isn't on. Too old to do diagnostics with, not opposed to buying a newer one, just don't have one yet. Do have an AFM disabler in the OBD port, tried with/without, no difference in power. Slightly rough idle, nothing I'd normally worry about, seems that this model is kinda known for that. There any known gotchas that I should be looking for?