Check Engine Light On

Made a mistake on the year - it's a 96 Infiniti G20. In order to get the actual code, I'd have to pay a repair place $$ for that service. The car starts up every time and idles well but as soon as you put it in gear, it stalls immediately. Seems to have gotten a lot worse since the cold weather hit Florida. It's my Granddaughters car and I'd really love to have it repaired but am afraid of getting ripped off. If I can get a few possible problems to give to the mechanic, I'd feel a little less vulnerable.