Xt350noob

Hey, I am new to the world of motorcycling but grew up riding 50's and owned a yz125. I am new to working on bikes and I recently purchased a 1987 Yama XT350 with 7k miles on it to learn to ride on and commute nearby to school and work. When I test rode the bike it rode fine but then after purchasing it and riding it home I noticed some problems. First of all, when I manage to start the bike and let it idle it is very rough and ranges through 1.5k to 2.5k rpms and throughout the idle it will randomly make a quick tick noise and shutter for a sec. Also sometimes when I put it into gear or turn the choke off it dies. When I do get it to run it can backfire sometimes and when I come to a stop I have to keep the rpms above 2 because otherwise the bike will just die. Please help the newb. Thank you.