1994 3/4 ton 4l80e shifting problems SOMETIMES

[brandon44]

my truck shifts perfect sometimes, other times it won't engage right away it slips then fully kicks in. Sometimes goes to limp mode. I can shut it off, and back on and it's fine I thinks is in the wiring some were, I've cheaked the fluid it's good, and has a new tps, i thought it was the shift selinods but wouldn't it happen all the time if there bad help would be appreciated 

[davester]

read codes from the computer.