with me it was the o2 censer
Low fuel pressure
In my experience with my Chevy it was a ground wire
have you checked your fuses?
Bad heater core.
The 2005 Cavalier could have a fuel leak. Have the entire fuel system checked, as a fuel leak can cause a dangerous fire.
Blown Head Gasket or Bad Cylinder Head
bad o-rings or not seated and tightened down properly
There are several things that can cause your 1995 Chevy Cavalier transmission not to go into drive or reverse. The most common cause is a lack of transmission fluid. A broken shifting fork will also cause the problem.
The 1997 Cavalier has two motor mounts, as well as a transmission mount. If the mounts are broken the motor can move around and cause damage to components under the hood.
The trans is electronically shifted so the sensor being bad is a likely cause.
You need to check all of the mounts. Get a manual to show you where they are.