Grand Prix SE V6

• Automatic transmission
• 95,000 miles

When turning the key to get started there would be delay and sometimes would have to try it twice for it to turn on. One time it did not start at all. My boyfriend had come and switched the gears (he mentioned that the car may not read its in park to start) and he started it right up. I had brought my car to fix this as well as the key getting stuck in the ignition and they replaced the shifter, which solved the key problem but a few months later my car would not start again and was the same exact situation. My boyfriend was able to switch the gears around again and started it right up. After some of my own research on starters, I believe it to be the Neutral Safety Switch (either out of adjustment or bad) or possibly the starter solenoid. My car is in the shop currently and they have no idea what is wrong. They indicated they can't diagnose it unless it acts up and it would start right up for them all day until finally at the end of the day it acted up one time. But they still can't find the problem and only mentioned that the starter isn't getting the power (which again can be from the solenoid or NSS). This is extremely frustrating b/c it makes the car unreliable and I have no idea what to do to fix it. I don't understand why they can't test the solendoid or NSS to see if they have gone bad and no one can explain anything to me in detail. I have a new iginition set and shifter--what else could it be linked to besides the starter? My battery is also fairly new and power is not the problem.