1996 GMC 5.7 C1500 code 1351

Hello,

I have a 1996 GMC C1500 that will not start on humid days. On the less moist
days it will start, but generally it cranks for quite a while then sputters after I
disengage the starter. When it finallly turns over it will normally die within a few
seconds 3 or 4 times before it will stay started. It gives code 1351 during this
process. I have replaced the coil, ignition control module, cap and rotor. I have
60 PSI on fuel pressure. Any ideas. I plan on replacing the pitails for the icm
and coil as well as the coil wire. Any additional thoughts? Thanks, Q.