Pontiac Grand Prix is it gunna last much longer

You must judge this for yourself. Without knowing anything about the car I could not say. If you think it is a POS then it it probably a POS.

Well the vehicle is 15 years old. Tires and other things wear out. It sounds to me like you need a better mechanic! The power steering pump was a misdiagnosis of a bad rack and pinion, in my opinion. The serpentine belt falling off is probably the result of the power steering pump not being put on correctly. Many times a perfectly good vehicle is ruined by poor repair facilities. But, a vehicle will wear out just like anything else. If every time you turn around it's something else that needs fixing and you're spending money after money to keep the vehicle running, it's time to move on! Hope that helps! Jim

I agree with everything that's been said. What kind of miles are on the car? They typically go around 200,000 miles with proper maintenance. If its 175K + then I wouldn't spend too much on it. If its considerably less than its likely worth it within reason. They are great cars. I've had a couple of them and almost bought another one when my last one got wrecked.