My '83 SD had this problem. There were three hood latches: the primary latch under the star in the middle of the hood, and two secondary latches , one on each side of the grille.
The passenger side latch was sticky and was harder to operate than the driver side. I had to wiggle the hood and push both hood latches together at the same time.
The fact that the hood is popping up indicates that the primary hood latch is opening fine. You need to push the secondary latch (the side that is sticking) toward the center of the hood while not letting the one on the other side relatch itself.
Once you get it open, take a look at the way it works. I'd lubricate all three latches, hinges, etc. Make sure you lubricate the hinged spring that pushes the latch back into its normal, outward, position.
Also take a look at the little black cylinders on the underside of the hood. I never fixed mine on my SD, but they move up and down; neither did I figure out what position they're supposed to be in, or if they are supposed to move at all... any ideas?
I'm haven't inspected my '84 to see if it's identical to my '83, but the hood latches work flawlessly. One you get good at getting a sticky one open, you can appreciate one that works fine
Robert W. Roe
1984 300SD 165K miles
[This message has been edited by Robert W. Roe (edited 08-09-1999).]