By '85 GM cars had fuel injection... No chokes... This is a "cold start" sensor... No adjustments... Just replace...

Yes - seems likely. But that was what we thought when my car was hard to start, idled rough at the lights, and ran like a dream the rest of the time. We replaced two sensors, but it made no difference. In my case it turned out to be an almost new coil that had only been replaced a couple of months earlier, which was only giving a weak spark. I'd have put money on it being a fuel problem, but it wasn't.

Your problem seems a bit different to mine, because with all the problems I was having, my car never actually stalled - just sounded like it was about to. The more I think about it, the more I'm thinking something to do with the fuel pump. Sometimes they get weak and although they are sorta pumping they are not pumping well.

As far as rust repairs go, you obviously want to do something cheap and cheerful that will keep it on the road a bit longer without spending much money. I'm usually in that position with cars, although I'm hoping for a longer life with my present one, which fortunately doesn't seem to be showing any signs of rust yet.

I used to be married to a spraypainter/panelbeater, so I picked up quite a few useful bits of info from watching him. He always had old cars and was always working on them. Since the divorce, I've not had much money (had even less when I was married) and always had to battle to keep a car on the road. I've had quite a few cars that needed patch up jobs at registration time so they would pass the inspection, so I learned to do my own rust repairs.

These were not meant to be a proper fix, and were not strictly legal, but they did the job of passing rego. The only rust they were really strict about was in structural parts of a car, where there was a safety issue. As long as there was no OBVIOUS rust, it was okay. I'm familiar with the crumpled up newspaper scenario - even a rag, and sometimes a bit of mesh across the hole. One of my cars (an old '74 Galant) really was that bad. I managed to register that car three years in a row by patching it up, and by the time I had finished and painted it, it looked pretty presentable. You could pick it if you looked close - it was not meant to fool potential buyers, but it was good enough for registration purposes. I ended up selling it for a few hundred dollars when the opportunity to buy a better one came up.

The stuff you mentioned that you mix up - the 'spackle for cars' is the thing you need - body filler. It comes with a tube of stuff which activates the setting process when you mix them, so you have to use it within a few minutes before it sets, while it's soft and pliable. It's a good idea to roughen up the surface of the area to give it a 'key' before putting it on. When it has set, you can sand it to make it smooth. I got an orbital sander, which definitely paid for itself for the number of times I used it, but if you don't have one you can just get sandpaper and sand it by hand - it's just harder work. The orbital sander makes the job so much easier. Start with rougher sandpaper, and work down to a smoother one. The stuff we used here in Oz is called 'wet and dry' and comes in a number of different grades. The higher the number, the finer the paper.

If you can paint the area, it will look a lot more convincing. If there are windows or trim or doorhandles etc nearby you have to cover those bits with masking tape or tape and newspaper so they don't get overspray on them. Here in Oz (I'm assuming you could get the same thing where you are) There is a range of spray paint in cans made in the manufacturer's colours for particular makes and models of cars. You should be able to look up the right colour for your car. They also have primer in cans that you put on first. Then two or three thin coats of the colour. The trick is to put it on thin so it doesn't run, and wait between coats. I got quite good at it after a while. The old Galant was a metallic green, and metallics are harder to blend in, but I was pretty happy with the result.

More recently I did some rust repairs around the windows of an '82 Holden Commodore I had, good enough for it to pass several years in a row. A series of mechanical failures were what killed that car. It became uneconomical to keep going with it.

Hope all this helps.