Having problems with my 1998 Pontiac firebird. When I sit with the air on my car sometimes start to shake or even smoke. I don't know if it's the exhausts or something dealing with it breathing. Whatever it is that's making the car not breathe cause while driving car has no pressure backed up until I come to a light and sit for a min. What could possibly be it? Pls help!? I should've gone to school for these situation.

A bunch of things can cause this.
It could be the engine idle speed is too low, can be caused by a faulty Idle Air Control valve. Watch the rev counter when it does it and see if it's very low. See if it rises when you turn off the air con. The air con puts a load on the engine which should be adjusted for by the IAC valve (automatically opens the throttle very slightly to keep the engine speed from getting too low).
Also possible to be fuel pressure, Mass Air Flow sensor, ignition coil, spark plugs or even a blocked air filter.
Is the check engine light on?
Try looking at Pontiac firebird forums. Google search firebird idle faults. Good luck.
https://www.google.co.nz/search?q=1998+Pontiac+firebird+idle+adjust&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=YbpsWavMPOrc8weH8qDYAw

https://www.google.co.nz/search?q=Pontiac+firebird+ide+problems&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=z8dsWcXfBOHDXsLtjoAN