I just got rid of my 1996 Nissan Altima. I had the same problem, not being able to start in park, only neutral. I am the original owner, since 1996. From 2000 until 3 weeks ago, it needed 32 visits for one problem or another. This year alone, i've spent $3500 CDN on repairs. Catalytic converter, and my second distributor in the life of the car.
Just got rid of it yesterday. Good riddance says I.