The Discovery or History channel did a special on this one night and went through the investigation. Based on what I saw, I believe this.
The aircraft set on the ground with the air conditioner running and heated up the fuel tank directly above it and created fuel vapors. After the aircraft took off, stray electricity got into a fuel sensor that created a spark. The fuel tank exploded and did major structual damage to the aircraft. It broke into and crashed. The black box had a missing part of data that came when sometype of shortage was created in the electrical system. This happened at the same time of the explosion.
The findings are correct.
But what about the guy in the grassy knoll? Oh wait, different conspiracy, sorry.
So, you did not witness the crash.
Your only source of information is a TV program, and you aren't exactly sure which program.
You mention that 'stray electricity' go into a fuel sensor.
How do you create 'stray electricity'? Where did it come from? How did it get into the tank, into the sensor?
Why can lightning strike an aircraft, and yet not cause fuel tanks to explode?
Why did the FBI take over the investigation from the FAA, when it is the distinct role of the FAA to do the job?
There were experienced pilots and flight-combat veterans who state they saw a missile. Why would you reject their word?
The FBI states the front half of the fuselage climbed 1000 feet after the 'explosion'. Do you really believe this is physically possible?