My blazer has been sitting for about 2 months untouched. It seemed to have small choke problems before. I started it today and it ran like absolute crap. It was shaking and started quietly backfiring at idle. When I tried to pull out of the driveway to drive it, it would not even backup. It started to move and then it just quit. It has never done anything like this before and besides a couple of choke problems when colder has run perfectly. Last time it was running it was much warmer outside than today. This is my second blazer and I have never had any sort of problem like this. Any ideas as to what this could be or what I can check to find the problem would be very helpful. Thanks.