i turen key and get fuel pump on,no crank at starter,if i retry key, it usually will crank and start.i have replaced ignition switch(white plastic switch afew months ago and it worked at that time).new starter and battery,pushing on wires at switch under dash does not change intermittent starting.would a bad ignition tumbler cause this?my key is pretty worn.

Unless you went with one of the top of the line German switches then I am betting on the switch.