You're welcome Rocky!
The TPS voltages looks good.
Then the IAC is working at least some because it is used to get the fast idle when started cold.
If the IAC did not work at all they tend to load up, or flood, when you try to start them, if you do not hold the gas pedal down.
The IAC still could need to be replaced, and I can't make the call without being there. We will not rule it out yet.
I would not order any parts yet. No part stands out as being the problem for sure.
The truck in the link I posted for photos has the same part number on the EGR valve as your truck. Make a note for future reference that your truck has a Port EGR system. Very few poeple will know how to test it.
I would test the fuel pressure, but it is not easy because there is no test port on these TBI trucks and the pressure should be tested with the engine running.
I would look in the distributor.
On these distributors the housing/upper bushing area can get so worn out that the shaft will move sideways so far that the points on the pickup coil pole piece get hit by the reluctor points on the shaft. When this happens the ECM receives compromised signal for RPM and timing issues.
If there is oil coming up the shaft and getting out onto the pickup coil – replace the distributor.
These distributors can also have problems because of loss of magnetism needed for the pickup coil to work.
If the magnetic material on the shaft in the reluctor wheel area is cracked into pieces replace the shaft or the whole distributor.
Photo of cracked magnet in this thread:
http://www.chevytalk.org/fusionbb/sh...e0b728a96e45b/
Keep looking until we find something that looks like a problem. Your communication skills are great so we should keep working at this instead of taking a guess and buying parts.