I have a 08 lt 3.5 impala. Has 55k miles. The car is a pita to drive. I mean rpm fluctuations like 50 rpm small but very noticeable and annoying . I do not have loss of power or code shown on display. s never stalled though. . The car sticks with highest gear all the time till half way down pedal. First gear changes like at 20 mph ( used to be like 45 when car drove good) . Each time car changes gears rpm goes up 1k for sec but doesnt jolt car just engine. These issues gradually started like in a few weeks. Car also has popping sounds in front of car when stopping and acceleration. Also car uses oil. Would say a quart. I use 5w30 synthetic with 4k intervel changes ( car comp reads 20 percent oil left when i change) .some say normal to use oil but i have a 03 mustang mach 1 and doesnt burn use any oil. I alreadt had a sensor replaced it cost me over 200 dollar. This impala also has bad locks. The door locks wont unlock all the way. And now driver door is getting misaligned when closing.