I have a 96 GMC Sierra with the 5.7 Vortech, back in November I replaced the engine due to a severe rod knock. For the first few days it ran like a champ then when I filled the tank I started having problems. My truck started hesitating and stumbling all over its self. I thought that it was the gas so I put some fuel treatment in it which never made a difference. I replaced several different sensors with no change. I finally took it to a shop and the problem was that it was not holding time, he would set it and it would jump 20 to 30 degrees. I opened it up to replace the timing chain and found 1/4 inch of slack in the passenger side. I made sure everything was lined up properly and I have good compression. I am getting spark, fuel, and air but no start. It came closer to starting when I pulled the #2 wire so I rechecked my timing and firing order but no luck. My plugs are burnt. I need to get this thing running again. Any ideas? Thanks.