Hey, I got a 91' firebird 305 tbi that had the same exact problem...it's your speed sensor or O2 sensor....(or both)
You can find the 1995 Pontiac Firebird 3.4 liter engine IAT sensor on the back of your engine. The IAT sensor will be a few inches above the transmission.
It is behind the Harmonic balancer at the bottom pulley on your motor.
If it has a 700R4, it is in the tail shaft of the tranny on the drivers side.
your bank 2 sensor is the o2 sensor on your passenger side exhaust manifold
on the 3800 V6 its below the throttle body
On the driverside firewall is first place I would look
Low voltage (high vacuum) at mass air flow sensor (or MAP sensor).
Bad resistor on key? Bad sensor in ignition lock?
The manifold absolute pressure sensor on a 1989 Firebird Formula is attached to the passenger side fire wall just above and to the right of the air conditioner evaporator housing. There is a three wire plug and a single vacuum line connected to the bottom.
I've had a problem with my O2 sensor and air filter causing my 1998 firebird to misfire.
Check your fuel filter, throttle position sensor , and timing
Most of the time it is the sending unit inside the fuel tank. This is a single pump. sensor assembly. Drop the tank and replace the pump and sensor.