eirrek

I have a 01 chevy 5.3, 198,000 miles. Just recently when i am reversing, then stop to put it into drive it dies. I then put it into park and it starts right up. This has been going on for a couple of weeks. Someone suggested it may be the neutral safety switch, not going into gear? So i started shifting it into 3rd then back up to drive and it wont die? I have been doing this trick for a week, and no problems. And now when stepping on the gas it stumbles/jerks then its fine. I bought the truck with 20,000 on it so i know the truck. Here is a list of things I have done within the last 6 months. All of these things have been done numerous times during me owning it. Plugs,wire,fuel filter,fuel pump,intake completely removed and cleaned, head gaskets was leaking on the outside no fluids mixing, and all the gaskets up, trans filter, shift solenoids, mass air,throttle position,idle air control, air filter, 2 O2 sensors. I did have dual exhaust coming out of 1 muffler, I lost a pipe had have a couple of holes in the exhaust. There is NO CHECK ENGINE CODES. Any suggestions would be helpful.