problems starting and misfire

I have a 96 grand prix se with the 3.1 engine. I have had alot of problems with the car not starting. At first it had the security light on so I thought it might have been the pass key 2 security system. It no longer does that though and i've taken the car to a pontiac dealership and all they told me was that my starter was bad. I just replaced the starter a couple months ago and it works most of the time. Can a starter work sometimes and not other times? I have had a new computer installed, got a new starter installed, and i'm kind of clueless. My friend says its not the starter but pontiac said that it was and that they hit it and it started up. So my question is can a starter act up intermitantly? I have also had another problem with the car feeling like it is shaking when I start it up. Both problems occur from time to time. I had the car looked at 3 times regarding this problem and was told that it was a misfire in the engine. I had a coil pack replaced but the problem still still comes and goes from time to time. I was told by autozone that I had a misfire on cylinder 4 one day when it had been acting up. Pontiac recently told me that I had a misfire on cylinder 1. Are my fuel injectors going bad? These 2 issues have been costing me lots of money and nobody seems to know how to fix them. Any ideas?

If the problem is the passkey 2 system would installing a remote start take care of the problem?