Most likely your safety neutral switch or your PRNDL swith is going bad Go to a transmission shop and have it replaced. Or possibly the linkage is loose. Also go to a transmission shop and have it repaired.
There is a switch that tells the car its OK to start the motor. The one for the gear shift being in the Park or neutral position sounds like its loose or out of adjustment. Unfortunately I am not familiar with the 99 and where it is. Hopefully someone else can elaborate.
The 1987 Pontiac Trans Am shifter knob is held in place with a retaining clip below the shifter knob. Push the retaining clip together and the shifter knob will raise off.
It is probably on the trans where the shifter linkage goes on the trans. If not there it's on the bottom of the shifter. but I suspect that its on the outside of the trans.
how to remove trans shifter cable ball socket from shifter ball
Automatic or manual trans?
twist it to the left
That depends on what trans it has. If the shifter is electronic then yes. If the shifter is not electronic then it is a three speed.
remove access plate on floor around shifter, 4 bolts hold the shifter onto the trans.
Automatic Floor Shifter - 25 results like the 6423 Shifter Automatic, B & M 81011 Street Rod Shifter Auto Trans Shifter Kits, 3160009 Quarter Stick Shifter ...
rod length is same
none, the trans am package came with a console shifter
Remove the access plate on the floor to expose the trans. disconnect the transfer case shifter as 2 of it's bolts are shared with the shifter on the trans. The bracket is held on to the 2 left hand shifter bolts and will have nuts on the top to remove, it is not possible to just move it out of the way without removing the other 2 bracket bolts further down on the trans. Then remove the 4 retaining bolts on the top of the shifter and pull it out.