I ordered 2007 GT which I received in August 2006. I only put 3000 a year on it and store it winters. Everything was great the first year-ran excellent. Standard tranny with 3:55 gears and it ran. Last summer in hot weather on a crowded city street it started to what I would call"load up". I had to put it to the floor to get it going with hardly any power. Once I cleared traffic and got on the interstate it seem to be ok. Since then it doesn't seem to have the power it had. Gas mileage is still good but sometimes it just doesn't want to go. It will idle evenly even when it's going through the bad spells but it just won't go. Any suggestions before I bring it to the dealer. It's bare naked stock just the way I bought it.
DRIVE IT MORE!!!!!!!!!!! It could be carbon buildup or many other symptoms from letting it sit so long. Do you start and let it run every so often(idle/drive)? Do you properly winterize it?
Sounds an awful lot like its going into limp home mode, no wrench symbol lighting up on the dash? It might be worth having a dealer check the computer to see if anything weird is going on.
See if the following helps: (1) Clear the ECM's adaptive memory by removing the battery's negative cable, and reattaching it after 15 minutes. (2) Recalibrate the gas pedal's and throttle body's drive-by-wire settings by turning the ignition to the "ON" position(do not start the engine), after the chiming sound stops smoothly press the gas pedal to the floor while counting 1001-1002-1003, release it quickly when it's fully depressed, wait 6 seconds, turn the key to the "OFF" position, wait 6 more seconds, and repeat the procedure 2 more times.
I'm going to guess fuel pump issues. I would also venture to guess you have oil or something on your throttle body. Take off your intake and take a look at it. If it's dirty, clean it and install an air/oil separator going from the driver side pcv to behind the TB
Thanks for the info everybody It's going to the dealer first and if they can't figure it out I will use all the suggestions. i'm new here but what a great source of info. Thanks again.