94 Z-28 5.7. Car starts and runs fine when cold, after it warms up and you let it sit for 10 minutes it starts fine but is low on power and sometimes stumbles and dies. It is not setting a SES light and once the problem goes away (in just a couple of minutes) the car runs great at all speeds until you shut it off again. it has a new GM Opti with less than 5k miles on it, the fuel pressure is 40psi at prime and does not drop. I tested the coil and am getting 9800 Ohms. Once the prblem goes away i have run the snot out of the car and It has no issues so I am totally confused..any ideas?

 

You can get a code without the light being on. If you have anyway to run a datalog or monitor whats happening it would help. Does it smell like gas when you first start it up until it runs better?

 

No it doesnt have a gas smell.