Good afternoon,

I am the original owner of a 1994 Chevrolet Silverado K3500 with the factory stock 454 and automatic transmission with 84,000 original miles.

The issue occurs once the coolant temperature surpasses 165 degrees (operating temp is around 205), when placing the vehicle in drive with my foot on the brake it starts intermittently stumbling or hesitating while stopped and idling.  This happens continually at random intervals while idling at stoplights for instance.  The engine will start to die, and then will 'catch' and start idling again.  However, it has never stalled.  When releasing the brake and hitting the gas it will sometimes slightly hesitate.  The truck accelerates cruises and behaves normally at all other speeds except for idle.

So far my attempts to correct the issue have been as follows:

Rebuilt the TBI, all new gaskets and brand new AC Delco fuel injectors.  (the issue was unchanged)

Using my Actron CP9690 I am able to read the trucks diagnostics, albeit limited due to the OBDI information available from the computer.

The IAC and coolant temperature sensors are original and working, however I have been unable to locate operating parameters as a reference for any of the sensors.

Do you have any suggestions as to what the issue may be?

How can I find the operating parameters for the information returned after scanning the OBDI?

If I need to change anything externally attached to the TBI, what is the best way to remove steel screws in the aluminum housing without breaking them?

Any assistance would be greatly appreciated.

Thanks