The following comments are based on my having interpreted what you wrote as meaning you already have all the realism setting options in FS2002 turned on.
The Cessna 152 is, relatively speaking, a fairly easy plane to fly in real life.
The small Cessnas are known for the fact that if you let go of the stick, they will, within reason, find their own straight level flight attitude.
This is not the case with the more complex aircraft. I wouldn't assume that what applies to a Cessna 152 will apply to a Boeing 747 in terms of flight stability and so on.
The other factor is the flight dynamics of the particular model's .air and aircraft.cfg files. Whilst Microsoft tried hard, they rarely got anywhere near as close as they could have done to simulating real aircraft behaviour. If you search the file libraries, you'll find plenty of modified and more realistic replacement files. Some of them will definitely give you a run for your money.
