I've had good luck with vinegar and evaporust. Both work well. Also make sure to check your plug boot and that it is making good contact with the plug wire. I have a 95 targa and when I first got it the plug wire was corroded causing it to stall and not start. It still had spark but just was too weak for it to start. Check that because I had problems with my plug wire for a while. And I saw your pictures of the gas tank and I have to say that really doesn't look too bad. I've seen much worse tanks running fine with rusty colored gas. It could be a problem but I doubt that it the main problem.