Recently my 1997 Jeep Grand Cherokee started running rough. The check engine light came on. We had the codes checked and it was an 02 sensor at fault. I had expected this due to a cracked exhaust manifold that would confuse the 02 sensors into mixing the fuel on the rich side to compensate. My fiancee tried JB Weld on the crack but it was too large so I ordered a new exhaust manifold. We put the new manifold on yesterday and after reassembling the engine, she (the car) won't start.( We had to remove the intake manifold, part of the serpintine belt, power steering pump, air box, and many assorted sensors were disconnected. These were all put back in place and reassembled before we started it. Replaced the air filter also) We checked for spark and all 6 cylinders are getting it. We are getting fuel to the fuel rail also. Really stumped as to why it wont start. (also the check engine light turned off) It will crank but not turn over. Any Ideas??