My 2005 CTS-V

[asshanson]

I think something is wrong with the tune with the ECU losing power for a couple days. I found out that the hesitation is the car missing or something along those lines, also explains the rougher idle. Above 2k the car pulls decent for partial throttle, but say in 4th below 2k up a hill it's hesitating non-stop, and I let off the gas a bit and it pops really loud, like a backfire. Does this indicate it's running really rich?

[mlomker]

Originally Posted by asshanson

Does this indicate it's running really rich?

Sounds like it. You might want to get a few gauges into the car. I've spent the last few weeks doing exactly that on my car...helps a lot with diagnostics.