There are several reasons why your car may be overheating. Check the thermostat to be sure it isn't stuck. If the car revs up and down, the timing may need to be adjusted.
Turn the throttle, revs go up. Let to, revs go down.
IT SOUNDS LIKE YOUR ICV. (IDLE CONTROL VALVE) YOUR CAR REVS UP AND DOWN RIGHT? JOSE
when your car revs up and doesn't go anywhere
it might be your jets
its because when you first set off your not at that point on the rev counter where the power output shoots up. on diesels, you get nothing till about 1800 revs and on petrols, nothing till about 4000 revs. hope this helps
Check coolant level Check the operation of the cooling fan
if the temperature goes up on ur gauge but it is not overheating means ur thermostat is no good
Try servicing the air filter.
A faulty thermostat might cause the temp gauge on the 2000 Nissan Altima to raise to hot when the car is not overheating. A faulty thermostat can cause the gauge to move up and down and might even turn the fan on.
The Brake booster needs replaced
When mowing it will idle up and down because of the amount and thickness of grass you are cutting. This is because the blades will struggle cutting thick grass so the engine needs more revs to keep the blades running at a constant speed and that is also why your mower may slow down because it has used the majority of revs to cut the grass and their are not many revs left to keep the wheels spinning The up and down revving could also be caused by a dirty/clogged air filter.