So I just bought a 95 Blazer and figured that I'd do a tune up just to make sure that I knew when it was done. But as I was changing the spark plugs the key got stuck in the ignition and wouldn't come out. So I changed the ignition lock as well now it wont start. It tries to start but backfires, the plugs have spark, and the firing order is correct (165432). I have no other idea why it wouldn't start now I bought it almost a month ago and never had problems. I have no idea what to do now? Or what it could be? I need some help!!