Why does my 1998 monte carlo z34 die while driving?

Occassionally, on my 1999 Monte Carlo, when I turn the key all dash and exterior lights come on normal but there is NOTHING to the engine; it doesn't even recognize that the key has been turned. After a while...

Is it hard to change a rear wheel hub assembly

How to remove and replace engine coolant temp sensor

It will run fine one minute then all of a sudden it just dies someime it eaey to start back up other times it not at my ropes end with it as you never know when its going to die

We are in the process of reassembling a 3.4 in a 2000 Monte Carlo, single, standard cam. Can someone tell me how to set the valve lash, if it needs it, or is it just torque? It appears to have hydraulic lifters....