I have a 2006 Jaguar XK8 automatic with 64k miles on it. When I step on the gas it feels like I am going nowhere, you really need to press down on the pedal since its not very responsive. I have issues accelerating in the low gears but still drives super smooth above 40 MPH. When I am in stop and go traffic it tends to even not down shift properly when I take my foot off the gas sometimes. There are no weird sounds but sometimes it'll chirp when it kicks into gear. A light came on that said "Gear box Fault" and it went into some sort of limp mode so I pulled over shut the engine off and started it back up. Light is gone but I don't want things getting worse. I changed the transmission fluid which didn't help and mechanic said he was surprised it was not very dirty and he said the electronics underneath look good, everything was dry and no leaks or water damage. (I assume he meant he checked the solenoids and TCM etc. when he said that but I didn't ask specifically.) I am wondering what else could it possibly be to cause the disconnect in the low gears like something isn't talking to each other? Could my transmission really be in bad shape with this little mileage on it? Where should I start with asking mechanic to do repairs to fix this issue since I am not very handy myself. Even simple tasks like spark plugs which I could normally do myself are much more difficult on this jaguar lol. Need some guidance please, thanks!