99 Bravada - Could it be the ignition switch?

About a month ago my 99 Bravada starting acting up (randomly would not start) eventually it just quit. We had it towed to a mechanic who replaced the fuel pump, when we went to pick it up it would not start the frustrated mechanic then keep the vehicle over night and called the next day to say that a 3rd party alarm system was causing the problem. After having it removed the guy said it was fixed and so we picked it up and drove it for 1 week and again it would not start. I then attempted to troubleshoot my self and found that when I would gently wiggle the key the fuel pump would takeoff and the thing would start. A call to the dealer was made for a new cylinder where I was politely told that was not the problem, according to them it was the fuel pump. Now I am completely confused, any help/advise. Could it be the ignition switch, tumbler ect

I have a 98 Bravada. A couple years ago i had the same problem.
after the fourth time i had it towed to the dealer. And after they replaced the passlock sender,the body control module to the tune of
1000.00 plus dollars it did end up being the ign. switch. I asked them
to check the switch they said it could not be the problem. But it was.
Needless to say i am in the process of suing for my money back on the needless repairs. So have them check the switch.

George