I am confussed and need help. I have a 96 obd2 and it went down on me a few weeks ago and I had some parts that I needed to install anyway so I tore it down and did it all. Well when it went down it would start then flood out and die and then finally it got to were it would not even start again. I figured since I had a coolant leak it was the opti shorted out. Well I installed a new water pump/opti-spark, plugs/wires, long tubes. When I tried to get the orginal o2 sensors out of the manifolds they wouldn't come out and rounded off so I just tried starting it without them on open headers and the car started and ran for about 30 seconds rough and then backfired a couple of times and I killed it, now it will not start again. The computer was also reprogramed for the LT's and the knock sensors was deleted along with the rear 02's.
What could cause it to not start or backfire and run rough when it did?

 

Does it have spark? Is it getting fuel? What have you checked so far?