fuel cutting out

[efini226]

I need some help please. Twice now ive been driving & my 2003 tahoe looses al fuel power as if im in neutral. I step on the gas and absolutely nothing happens. The electrical is fine. The truck sputters on the side of the road & dies. The first time, i waited a few minutes after unsuccessful start cranks and it finally started and no problems for about a month. Next time, things got worse including loud knocking or banging sounds from the engine area and I had to have it towed. My mechanic says that it runs great. He finally got an error code saying that either the crank shaft was off or the catalytic converter was not installed right. Neither of these two things have ever been worked on, so he said that it cant be either one. CAN ANYONE PLEASE HELP ME?