Possible reasons:
1. Dirty or worn transmission fluid: Dirty or worn transmission fluid can cause transmissions to slip and lock up, causing your vehicle to slow down.
2. Faulty torque converter: The torque converter connects the engine and transmission, and if it is faulty, slippage can occur, causing drag.
3. Worn clutch clutches: The friction plates in clutch packs wear out over time, which can cause gear slippage and braking.
4. Clogged hydraulic passages: Clogged passages can prevent transmission fluid from moving properly, leading to shifting and braking problems.
5. Faulty Engine Speed Sensor: A faulty engine speed sensor can provide inaccurate engine speed data, which can lead to improper shifting and braking.
6. Electrical Problems: Electrical problems, such as faulty solenoids or wiring, can cause problems with shifting, resulting in braking.
7. Faulty Transmission Control Module (TCM): The TCM controls the transmission, and if it is faulty, a number of problems can occur, including braking.
8. Transmission Speed Sensor Problems: The transmission speed sensor tells you how fast the transmission shaft is rotating, and if faulty, it can cause incorrect shifting and braking.
9. Drive shaft problems: Worn or damaged driveshafts can cause vibration and noise, as well as drag.
10. Faulty Brakes: Worn or damaged brake pads or rotors can create friction when you release the gas, resulting in braking.