your car must be too old
no u hav 2 change gears when the car is on its time to get a new car if this is the case
3
Your Transmission Fluid is very dirty. Change it and flush it first.
You need to hit the cluch before you change gears
1200-1400.
In a car-usually clutch is shot
When driving a car with an automatic transmission up a steep hill it is not necessary to shift gears. The car will do that on its own when necessary.
Once you know which relay to change, about 30 seconds.
You have not given enough information for a reliable answer. In these circumstances the best thing you can do is take the car to a reliable transmission shop.
it has a light that comes on to tell you when to change gears in a manual car, really just for show and the light can be adjusted to come on at whatever rpm you desire as long as the car can rev as high as it is set before the revs stall. in reality you change gears by ear and not even by looking at the taco let alone a light.
Best off to have the job done at a good shop. It all has to be adjusted and shimmed. If the car has say 290's in the back, then 343's would be good, but then, how much fuel would you really save? The crown as is, gets fairly good milage for the size of car. The cost to change the gears is around 300 to 500 bucks. The lower the gears the harder to take off, but with a set of higher gears, the car will take off easier, thus saving fuel that way. Personally, I don't think you will save what you really want to save.
If it is an automatic transmission, the speed of the engine (in rpm) is what makes the gears change. Accelerate too much and it will fly up through the gearbox when it is not supposed to. If it is a manual transmission, the gears shouldn't change without the clutch being depressed and you manually changing gear; at most, it will simply disengage and cease turning the wheels.