I need your honest opinion

I say quit looking at it from an investment perspective, unless that is all it is, an investment. If you bought this car from a emotional perspective, than you need to stay emotionally attached to it, on the condition that it is within your means to fix it. If it is within your financial and physical know how to fix it, then fix it, and enjoy.

If you sell this car, and get another, then you may end up in the same boat, with a car you can't fix.

I would only sell the car on these conditions:

It's not the car you wanted to begin with.
It's beyond financial ability to fix it.
It's beyond physical ability to fix it.
You found a better car than the one you have now.
You found a car that you desire more than the car you have now.
You no longer are emtionally attached to your car.
Someone else wants your car more than you do, and is willing to offer a nice price for it.