flames everywhere!

Hi all, just bought a 72 chevy to kind of tinker on and learn a little about restoring. Problem I have with it is fire shooting out of the top of the carb. I checked the firing order a week ago and the back 4 spark plug wires on it were crossed. It ran a ton better after I fixed that (gee go figure), drove it around a bit, ran fine, little sluggish but I dont think its been run for a little while. But the fire didnt happen after I fixed it. I went out to start it yesterday and the fire is back and it seemed real sluggish to start. What do I do??

recheck firing order and timing.

then preform a cylinder leak down test.

checked firing order, replaced points, condenser, and distributer cap. That seemed to help. I also adjusted the timing (best I could without a timing light). Thanks for your help. Now I just have to figure out where all the white smoke from the tailpipe is coming from :)