Any vaccum lines or the intake manifold it is 2 peices, I would look in to the vac lines. !warning! this is Dangerous to find on your own but you can take a (SMALL SPRAY BOTTLE) and gently AND slowly spray around the Vaccum lines till the engine Idle changes when it does there is the leak.
That would be your LOW engine coolant light You can view the 1999 Mercury Mystique owners manual online at : www . motorcraft service . com ( no spaces ) Click on Owner Guides
The mass airflow sensor would be between your engine air filter box and the big engine air intake tube
For a 1996 Mercury Mystique, the recommended engine oil is 5W30 (4.5 quarts) for a 4 cylinder, and 5W20 (5.8 quarts) for a V6. Given the vehicle's age and assumed high mileage, it would also be acceptable to go with a heavier weight (higher viscosity), such as a 10W30 instead of 5W20 or 5W30. It also depends on the engine condition and your climate.
check your timing belt
It could have a pluged fuel filter or a pluged fuel inlet screen. Make sure the fuel pump has a full 12 volts.
im wandering where the transmission filter is on my 1996 mystique with a 4 cylinder.the filter has to go inside somewhere but not sure.if this is free it would be a huge help.perry
I'm not a mechanic / technician but your check engine light would probably come on , the engine would run cooler , your gas mileage would be worse , your emissions would be higher , your heater wouldn't put out hot air . There are probably other problems , I'm assuming that the water pump is working fine
nothing unless the mechanics took your car off roading
A mechanic would be able to help you with doing this. It is best to do it this way to avoid any problems later on.
rings or seals
I just paid $500.00 to replace all brake pads and the front rotors
Don't have an exact figure but judging from similar Ford models, expect the cost to be quite expensive