I have noticed the same thing with the 2000 and earlier cars. They seem to be very heat soak sensitive compared to 2001 and up.
The IAT in the 97-2000 C5's is very close to the radiator as well. Not an issue while driving on the highway but it certainly makes a big difference in stop & go and hot restarts. I have seen the IAT temps drop 35+ degrees with medium throttle in less than a 3 block stretch on a 2000 C5 after a hot restart.
I have thought about either moving the IAT ahead of the MAF or converting to the 5 wire 2001-up MAF as a solution on the C5's. Not sure if it's possible on an F-body.
Any other ideas?
EC